What's happening

Russia has given Ukrainian forces in Mariupol a fresh ultimatum to lay down their weapons by 11:00 GMT on Wednesday. They're holed up in a huge steelworks complex at the moment.

The port city is surrounded but still hasn't fallen, and Ukraine's foreign minister said Russia has decided to raze it to the ground.

Around 130,000 citizens have been blockaded in the besieged city for 50 days and are struggling to find food, water, and medicine, the city's deputy mayor says.

Why Mariupol matters

• Securing land: Capturing Mariupol would leave Russia in control of a vast swathe of southern and eastern Ukraine
• Strangling the economy: It's home to an important port, which in normal times is a key export hub for steel and coal
• Propaganda opportunity: Mariupol is home to a Ukrainian militia unit called the Azov Brigade, which contain far-right extremists. Although they form only the tiniest fraction of Ukraine's fighting forces, it has been a useful propaganda tool for Moscow
• Morale boost: It would help the Kremlin to show its population - through state-controlled media - that Russia was achieving its aims

Get more detail from our security correspondent Frank Gardner here.

Joel Gunter
in Kyiv, Ukraine

A marine commander in the last Ukrainian stronghold in the besieged city of Mariupol issued a video message in the early hours of Wednesday morning saying his men might have only hours left.

In a video sent to the BBC and other media, Major Serhiy Volyna said his troops would not surrender, but he pleaded for international assistance for the 500 wounded soldiers and hundreds of women and children he said were hiding with them at a steel plant in the city.

"This is our last address to the world. It may be our last one ever. It is possible that we have just days or hours left," Major Volyna said.

"We call on world leaders to help us," he added. "We urge them to organise an extraction to take us to a third country."

The Azovstal Iron and Steel Works - a massive, four square-mile plant - has become the last redoubt of the Ukrainian resistance in Mariupol.

"The units of the enemy exceed ours dozens of times, they prevail in the air, in artillery, in ground troops, and in machines and tanks," said Major Volyna, who is a commander of the 36th Marine Brigade.

He declined to say how many Ukrainian troops were left in the plant but he said they had "good fighting spirit". The situation for the wounded was "very bad" however. "They are in a basement, they are just rotting there," he said.

Mariupol has been a strategic goal for Russia since its forces invaded Ukraine in February. The Ukrainian president, Voloymyr Zelensky, told the BBC last week he believed up to 20,000 people may have been killed in Mariupol by the Russian bombardment of the city, and unknown numbers taken into Russian territory.

More now on a preliminary agreement for a humanitarian corridor to evacuate women, children and the elderly from Mariupol.

Ukraine hopes to send 90 buses to the besieged city on Wednesday to evacuate about 6,000 women, children and elderly people, the city's mayor says on national television.

Vadym Boichenko says he hopes a preliminary agreement with Russia on establishing a safe corridor would be confirmed and respected.

About 100,000 civilians remain in Mariupol and tens of thousands have been killed in the Russian siege of the city, he adds.

Image source, Getty Images

Here's a look at the latest from Ukraine.

On the ground

• Russia's invasion is focused on eastern Ukraine. The opposing troops remain locked in combat along a 300-mile (480km) frontline
• The Russian defence ministry has given Ukrainian forces, who are holed up in the Azovstal steelworks complex in the port city of Mariupol, a fresh ultimatum, to lay down their weapons by 1100 GMT on Wednesday
• Not a single Ukrainian soldier accepted the same offer on Tuesday, the ministry said in a statement
• But Ukraine has reached a preliminary agreement with Russia to evacuate civilians, the deputy PM says. These have been hard to implement in the war so far
• The UK MoD has accused Russia of "indiscriminate attacks" in the port city of Mariupol

• In the face of Moscow's onslaught, Ukrainian troops have so far held the line, according to the General Staff of Ukraine's armed forces
• Ukraine also claims to have sprung counter-attacks retaking the town of Maryinka, near Donetsk
• Ukraine's President Volodymyr Zelensky said if Ukraine had access to better weapons, "we would have ended this war"

In diplomacy:

• Ukraine's allies in the West have vowed to boost military aid, providing Kyiv with additional military aircraft
• The Biden administration is reportedly planning to announce another $800m (£615m) in military aid

• UK Prime Minister Boris Johnson said he was supplying Brimstone anti-ship missiles and German Chancellor Olaf Scholz said Berlin would provide finance to help Ukraine buy German-made weapons.

Updates have been brought to you by Vikas Pandey and Andrew Clarance in Delhi, handing over to our colleagues Claire Heald, Emily McGarvey and George Wright in London.

Ukraine has reached a preliminary agreement with Russia on establishing a humanitarian corridor to evacuate women, children and the elderly from the besieged city of Mariupol on Wednesday, Ukraine's deputy PM says.

"Given the catastrophic humanitarian situation in Mariupol,this is where we will focus our efforts today," Iryna Vereshchuk wrote in a post on Facebook.

As we've been reporting, people have been trapped in the key strategic port city for weeks without supplies of food, water and medicines. Here's why it's so important a target for Russia.

In the past, such evacuation corridors have been fraught with difficulty to set up and implement.

Russian troops have been accused of blocking bus convoys at checkpoints. Russia has also been accused of forcibly relocating thousands of civilians to Russia or Russian-controlled areas.

Away from the siege in Mariupol, this week has seen Russia launch a new military offensive along its 300-mile eastern front with Ukraine.

The UK Ministry of Defence , externalhas set out its latest assessment of the situation on the ground.

It says Russia's military presence there continues to build, while fighting in the Donbas region is intensifying, as Russian forces seek to break through Ukrainian defences,

Russian air activity in northern Ukraine is likely to remain low since its withdrawal from north of Kyiv, an intelligence update says.

"However, there is still a risk of precision strikes against priority targets throughout Ukraine," it adds.

"Russian attacks on cities across Ukraine show their intent to try and disrupt the movement of Ukrainian reinforcements and weaponry to the east of the country."

You can read more on the new offensive here.

A little more now from Deputy Mayor of Mariupol Sergei Orlov who says there are around 130,000 citizens still living in Mariupol who have been in a blockade for more than 50 days and are suffering from the lack of food, water, medicine, and help.

Citizens who are living through continuous shelling and air strikes are encountering "a lack of everything, a lack of life," he tells BBC Breakfast.

Orlov says Ukrainian soldiers in Mariupol are finding it "very hard" to defeat the Russians, who are surrounding the Azovstal steel plant.

He says Russian troops continue to use hard weapons and carry out air strikes and shelling from warships with missiles, making it difficult for Ukrainians to defeat.

He says Ukraine needs hard weapons as soon as possible to retain the city.

One of the last remaining fighters holding out at the Azovstal steel plant in the city of Mariupol is Olena's cousin Maks.

"I would never have imagined my cousin to become a true hero of Ukraine," she tells the BBC.

The besieged southern port city has faced intense fighting for several weeks and is surrounded by Russian forces. But Ukrainian officials say its soldiers will fight until the end.

She says she has has imagined the worst, but she is very proud of him.

Image source, Getty Images

There are many civilians stuck in the besieged Azovstal factory, the deputy mayor of Mariupol says.

Russia has given a new deadline of 1100 GMT (Wednesday) to Ukranian troops in Mariupol to surrender, but Ukraine has vowed to continue to defend the port city.

Russian-backed fighters are reportedly trying to storm the Azovstal steelworks, where Ukrainian troops and civilians are said to be holding out.

“I can confirm that there are a lot of civilians," Sergei Orlov tells the BBC's Newsday.

"It’s mostly citizens of nearest destroyed buildings and a lot of workers of steel plants. They know that steel plants had good bomb shelter and some stocked food and water in the bomb shelter. That's why they decided with their families to live in this bomb shelter.”

No help for those in the factory is currently possible, he says.

"They have an absolute lack of everything. A lack of water, food, medicines, help, and Russia totally blocks everything, any humanitarian help or evacuation," he says.

"All this news about possibility to go away, to leave either Mariupol or Azovstal plant territory is fake.”

Image source, Ukraine military

Russia's main focus remains the southern port city of Mairupol, the Ukrainian military says. Its troops are continuing assaults on the Azovstal steelworks, where Ukrainian troops and civilians are said to be holding out. The military also says:

• Russian forces continue their large-scale invasion in eastern Ukraine to establish full control over Donetsk and Luhansk regions.
• Russia continues to bomb civilian and military structures in the country.
• In Donetsk and Tavriya, Russian troops continue shelling along the front lines, trying to find weak spots in the Ukrainian defence.
• Russian troops are trying to launch a military operation in the Ukrainian village of Popasna in Luhansk in eastern Ukraine.
• After attempts by Russian forces to storm Rubizhne and Severodonetsk localities, around 130 wounded troops were taken to a local hospital.
• Ukrainian military have repulsed 10 attacks by Russian forces in Donetsk and Luhansk over the past 24 hours.
• Twelve tanks, 28 armoured vehicles and one artillery system have been destroyed, and Ukraine's air force has hit nine targets - one plane, one helicopter, six UAVs and a cruise missile.

The BBC has not been able to independently verify these claims.

Direct communications between the International Atomic Energy Agency (IAEA) and the Chernobyl nuclear power plant have been restored, the IAEA says.

Russian forces held Chernobyl for five weeks before withdrawing on 31 March. The IAEA lost contact with the nuclear power site on 10 March.

“This was clearly not a sustainable situation, and it is very good news that the regulator can now contact the plant directly when it needs to,” IAEA Director General Rafael Grossi said in a statement.

Grossi added he would lead a team of experts to Chernobyl later this month to carry out a series of assessments.

Image source, Reuters

Image source, Ukraine military

In his nightly video address to his country, Ukrainian President Volodymyr Zelensky said if Ukraine had access to better weapons "comparable to the ones used by Russia, we would have already ended this war".

President Zelensky said that "in all my interviews and negotiations with leaders of the democratic world, it is unfair that Ukraine is still forced to ask for what its partners have been storing for years".

He said that if these countries have the weapons and ammunition that Ukraine needs, "it is their moral duty to help protect freedom, to save the lives of thousands of Ukrainians".

He further added that if his country got the weapons which have been promised to them in the coming weeks, it will save the lives of thousands of people.

President Zelensky added that the intensity of Russian firing in Kharkiv in Donbas and in the Dnipropetrovsk region has increased, even targeting civilian structures.

"The fate of tens of thousands of Mariupol residents who were relocated to Russian-controlled territories is unknown," Zelensky said.

This comes as Russia's defence ministry has issued a fresh ultimatum to Ukrainian troops holding up in the besieged city of Mariupol to lay down arms.

Paul Kirby
BBC Europe Editor

Image source, Getty Images

Russia has moved most of the focus of its war to eastern Ukraine, after pulling back its forces from near the capital Kyiv.

Ukraine's leader Volodymyr Zelensky says the battle for the area known as Donbas has begun and promised to fight for "every metre of our land", meaning Russia's new offensive could herald a protracted conflict.

If Russia were to conquer both big regions, it would give Vladimir Putin some sort of achievement from the war. The next step would then be to annexe Donbas, just like he did with Crimea after a discredited referendum in 2014.

And if it came before 9 May, he would even be able to celebrate on Victory Day, when Russia's military still marks the defeat of Nazi Germany in 1945.

Read more about why Russia is working to capture Ukraine's east

Image source, Getty Images

The Russian Defence Ministry has given Ukrainian fighters, who are in an industrial complex in the besieged port city of Mariupol, a fresh ultimatum, according to a Reuters report, external.

"Russia's armed forces, based purely on humanitarian principles, again propose that the fighters of nationalist battalions and foreign mercenaries cease their military operations from 1400 Moscow time on 20th April and lay down arms," the Russian Defence Ministry said.

Not a single Ukrainian soldier accepted the same offer on Tuesday, the ministry said in a statement.

Russian-backed fighters are reportedly trying to storm the Azovstal steelworks in Mariupol where Ukrainian troops and civilians are said to be holding out.

In a post on Telegram, the Mariupol City Council said that despite the advantage of the many Russian troops in the city, they still have not been able to take Mariupol, and so "they want to level" the steel plant.

It further said that Russia was not deterred by the fact that civilians are also taking refuge in the complex.

Ukrainian President Zelensky said the situation remained "as tough as possible without any changes", and the fate of tens of thousands of civilians remains unknown.

Ukraine war in maps: Tracking the Russian invasion

Image source, Getty Images

In case you're just joining us, here's a look back at the latest from Ukraine.

On the ground

• Russia's large-scale invasion of Ukraine's east is underway, and the opposing troops remain locked in combat along a 300-mile (480km) frontline in eastern Ukraine.
• In the face of Moscow's onslaught, Ukrainian troops have so far held the line, according to the General Staff of Ukraine's Armed Forces. Ukraine also claims to have sprung counter-attacks on their enemies, and say they've retaken the town of Maryinka near Donetsk.
• And the UK's Ministry of Defence said Ukrainians have repelled "numerous" attempted advances. Russia is still hampered by "environmental, logistical and technical challenges", the MoD said.
• The MoD also accused Russia of "indiscriminate attacks" in the port city of Mariupol. Russia's defence ministry once again called on Ukrainian troops holding out inside Mariupol's Azovstal steel plant to lay down their weapons on Wednesday. Not a single Ukrainian soldier accepted the same offer on Tuesday, the ministry said in a statement.

Image source, Getty Images

In diplomacy

• Ukraine's allies in the West have vowed to boost military aid to Ukraine, providing Kyiv with additional military aircraft to expand the country's fleet.
• The Biden administration is expected to send another major military aid package to Ukraine, in addition to the $2.6bn (£1.9bn) in security aid already sent since the Russian invasion began.

• Fiona Hill, a former Russia adviser at the White House, tells the BBC that President Vladimir Putin is "not in the business of compromise", and that chances of negotiation with him are slim.
• UK Prime Minister Boris Johnson said he was supplying Brimstone anti-ship missiles.
• German Chancellor Olaf Scholz said Berlin would provide finance to help Ukraine buy German-made weapons.

This is Jude Sheerin and Holly Honderich handing over to our colleagues Vikas Pandey and Andrew Clarence in Delhi, as they bring you the latest.

Image source, Getty Images

Netflix is citing the war in Ukraine as one of the reasons it has reported a drop in subscribers for the first time in a decade.

The streaming giant joined a Western corporate boycott of Russia over its invasion of Ukraine.

The decision cost the company 700,000 new accounts, Netflix said.

Netflix is now facing a class-action lawsuit from its former Russian subscribers.

The firm suing Netflix has argued blocking services in Russia is a violation of subscribers' rights.

A Russian tycoon has blasted Moscow's "massacre" in Ukraine and called on the West to end the "insane war", in a profanity-laced Instagram post.

"I don't see a SINGLE beneficiary of this insane war! Innocent people and soldiers are dying," wrote Oleg Tinkov, 54, in Russian.

According to him, "90%" of his fellow Russians are also against this war. The remaining 10% "are morons" he said.

Tinkov, one of Russia's most well-known entrepreneurs, founded Tinkoff Bank in 2006.

On Instagram he added: "Waking up with a hangover, the generals realised that they have a shit army.

"And how will the army be good, if everything else in the country is shit and mired in nepotism, sycophancy and servility?"

Before Russia invaded Ukraine in late February, Tinkov's wealth had been estimated at more than $4.4bn (£3.4bn).

But he has since lost his billionaire status as shares in his bank have plummeted, Forbes reported last month.

In a statement, Tinkoff Bank said it would not comment on the "private opinion" of its founder, saying he no longer makes decisions for the brand.

Image source, EPA

Ukrainian troops have so far held the line against a broad Russian offensive in the country's east and in some places have successfully counter-attacked, according to the General Staff of Ukraine's Armed Forces.

In an operational update posted to Facebook, the general staff said while Russian forces had attacked Ukrainian forces and critical infrastructure in Kharkiv, a Russian offensive south of Izyum failed after heavy losses.

Additionally, the Ukrainians say their troops managed to retake the town of Marinka in the Donetsk region after launching a counter-offensive there.

The update also claims that Russia is continuing to move forces from Belarus into Russia to redeploy to Ukraine and that Russian aircraft have continued to strike targets in Ukraine from Belarusian facilities.

As Russia opens up its offensive on the eastern front in Ukraine, President Vladimir Putin is "not in the business of compromise”, according to Fiona Hill, a former Russia adviser at the White House.

Speaking to BBC Radio 4’s Woman’s Hour, she said Putin wants to see "what he can achieve on the ground before he’s ever going to be in any kind of mood to have a serious negotiation".

She said the chances of any kind of success or breakthrough are pretty slim right now unless the military operation is blunted and they feel that they can’t push any farther forward.

“Vladimir Putin and the people around him genuinely think that we’re trying to emasculate him or to disrespect him when the US and other delegations show up with women," she added.

"This is a misogynistic, sexist set-up in and around the Kremlin. Yes, there are women there but they’re not in the most prominent positions.”

Image source, Reuters

Peter Chumak, who's lived in London for 22 years, returned to Ukraine for family reasons just before Russia invaded.

Because he's a Ukrainian citizen he was ordered to remain in the country to help with the war effort. Seven weeks later the military alllowed him to return to the UK.

The BBC interviewed the family when Chumak's wife, Nicola, was trying to get him home, and has spoken to them again now he's back.