Image source, ROSCOSMOS

Russian cosmonauts have arrived at the International Space Station wearing Ukrainian colours, in what appears to be a statement opposing the invasion.

The three men were the first new arrivals since Russia attacked its eastern neighbour last month.

They were warmly welcomed on board, hugging and greeting their fellow American, Russian and German crew.

The trio wore bright yellow space suits with blue accents, instead of their standard-issue blue uniform.

Read more here.

Image source, Getty Images

Poland's Prime Minister Mateus Morawiecki has urged the EU to impose a total ban on trade with Russia.

Morawiecki says he wants to sea a "trade blockade" by sea and land "as soon as possible", Reuters news agency reports.

"Fully cutting off Russia's trade would further force Russia to consider whether it would be better to stop this cruel war," he says.

The EU has already imposed trade restrictions on Russia in some key sectors, including luxury goods, steel and energy. But Poland - which shares a 535km border with Ukraine - has been among those pushing for tougher sanctions on Russia.

Read more: What sanctions are being imposed on Russia?

Image source, Reuters

If you're just joining us, or catching up on events, here are some of the latest developments from Russia's invasion of Ukraine:

• Fighting is taking place in the streets in the centre of the besieged port city of Mariupol, which is hampering efforts to rescue people trapped under the rubble of a theatre shelled on Wednesday
• The situation in the city is desperate - with as many as 300,000 civilians unable to evacuate - after Russian troops were able to work their way through armoured columns
• Mariupol mayor Vadym Boychenko has told BBC Ukrainian forces are "doing everything they can" to hold their positions, but that "forces of the enemy are larger than ours"
• An extended curfew has been announced in the south-eastern Ukrainian city of Zaporizhzhia, amid fears the city may be in the path of a possible Russian advance up from Mariupol
• Meanwhile, Russia has said its forces used hypersonic missiles - cutting edge weapons able to travel at more than five times the speed of sound - to target an underground arms depot in western Ukraine
• Ukraine's President Zelensky has urged Russia's President Putin to join him for peace talks "without delay", saying it's "the only chance for Russia to reduce the damage of its own mistakes"

Appalling scenes have emerged from a military base in Mykolaiv in southern Ukraine.

Belgian reporter Robin Ramaekers who visited the scene this morning has spoken of at least 80 bodies being pulled from the rubble, with "many more underneath".

The death toll hasn't been confirmed by Ukrainian authorities as it involves a military site, and the BBC has not been able to verify the reports.

Last night footage from the site showed a little girl being pulled out of the rubble, and her condition is unknown.

Here are some of the photos that Ramaekers, a reporter for Flemish public broadcaster VTM, has filed this morning from Mykolaiv. "They're continuing to search for bodies here in Mykolaiv, at the same time there's another air raid siren, so everyone down the bomb shelters," he says.

Mykolaiv Mayor Oleksandr Senkevich has said there was no time to sound air raid sirens before the raid as missiles were launched from the nearby Kherson region, to the south-east.

The Kherson area has recently been occupied by Russian forces, who invaded Ukraine from Russian-annexed Crimea.

Image source, Reuters

Former UK Prime Minister Gordon Brown wants a new international tribunal to be set up to investigate Vladimir Putin for his actions in Ukraine.

Brown says the war has seen the indiscriminate bombing of civilians, which is against international law, as well as breaches of humanitarian ceasefires and "nuclear blackmail".

The former PM has told the BBC that since the fall of the Berlin Wall "we've assumed that democracy and the rule of law will prevail", but that Putin was "replacing that by the use of force".

"If the message is not sent out now then we face aggression in other countries which may go unpunished as well."

Asked if he considered the Russian president to be a war criminal, he replied: "That's what President Biden said, and that's my view."

Brown is among 140 academics, lawyers and politicians to sign a petition calling for a legal system modelled on the Nuremberg trials of Nazi war criminals after World War Two.

Read more on this story here.

Image source, Getty Images

We reported earlier that Russia said it had used hypersonic missiles to target an underground weapons storage unit in western Ukraine.

But what type of weapon are they?

• Hypersonic missiles can fly in the upper atmosphere at more than five times the speed of sound
• They are considered more manoeuvrable than conventional missiles and are more capable of avoiding interception from air defence
• Russia's defence ministry said the missile used to target the arms depot in Ukraine was capable of reaching targets at a range of more than 2,000km (1,242 miles)

• Last year, Russia said it had successfully test-fired a hypersonic missile from a frigate in the White Sea off its north-western coast
• It said it aimed to include the weapon when arming Russian cruisers and submarines
• Along with Russia, China, the US, and at least five other countries are working on hypersonic missile technology

For more on this listen to: The Inquiry - What are hypersonic missiles and why do they matter?

Image source, Getty Images

Ukraine's general staff has claimed that over 14,000 Russian troops have been killed in the first three weeks of Moscow's invasion of the country.

In an operational update posted to Facebook, Ukrainian officials said that approximately 14,400 Russian soldiers have been killed.

The update also said that Moscow has lost a huge amount of military equipment, including around 1,470 armoured troop carriers, 60 tanks and over 100 fighter jets and helicopters.

The BBC cannot independently verify the claim, though Western intelligence sources have suggested that around 7,000 troops have been killed and between 14,000 and 21,000 more have been injured.

It comes as Ukrainian forces claimed to have killed a fifth Russian general.

Lieutenant General Andrei Mordvichev would be the most senior Russian commander killed in the conflict so far, though the BBC cannot independently verify the claim.

Hugo Bachega
BBC News, Lviv

Image source, Getty Images

The mayor of the besieged Ukrainian city of Mariupol says street fighting in the city centre is hampering efforts to rescue hundreds of people trapped inside the basement of a theatre that officials say was bombed by Russia on Wednesday.

Vadym Boychenko tells me that teams are only able to clear the rubble and remove people when there's a lull in fighting.

"There are tanks... and artillery shelling, and all kinds of weapons fired in the area," he says.

"Our forces are doing everything they can to hold their position in the city, but the forces of the enemy are larger than ours, unfortunately."

He couldn't give an estimate on how many more people had managed to leave the area in the last 24 hours.

On Friday, authorities said 130 people had managed to escape and that more than 1,000 were still in the basement, which withstood the attack.

Russia denies shelling the building, which had been clearly marked as a civilian shelter.

The strategic port city has been surrounded by Russian forces, and an estimated 300,000 people are trapped without electricity, running water and heating.

Boychenko also said 40,000 people had managed to leave the city in the last five days, and that 20,000 others are waiting to be evacuated.

Wyre Davies
BBC News, Zaporizhzhia

Image source, Reuters

An extended curfew has been announced in the south-eastern Ukrainian city of Zaporizhzhia, where a nuclear power plant was shelled earlier this month.

The curfew will begin today at 16:00 local time (14:00 GMT) and end at 06:00 Monday, authorities have said.

Details about the reason for the lockdown were not provided, but the city - which has seen thousands of refugees arriving from nearby Mariupol - continues to come under sporadic rocket attacks from Russian positions.

It could also be that the city may be in the path of a possible Russian advance up from the besieged port city of Mariupol.

Image source, Getty Images

A Ukrainian MP has described conditions in the besieged city of Mariupol as "medieval".

Dmytro Gurin, an MP whose parents are trapped in the south-eastern city, told the BBC's Today programme that supplies of food and water in the city are reaching dangerously low levels.

"People are out of food, and more importantly out of water," Gurin said. "And several of days ago, tanks started to shoot nine-storey buildings, so people cannot get out. Everybody is sitting in their apartments and basements thinking whether they will die in the next hour".

"The shelling never stops and the shooting never stops," he added. "Airplanes, they drop hundreds of bombs over 24 hours."

Gurin also expressed pessimism over the prospect of additional humanitarian corridors from the city being established, saying "the Ukrainian side are trying to have an agreement and open it, but Russia, almost always its only words".

He added that the bombardment unleashed on the city by Russian forces has rendered it unrecognisable.

"From photos I have seen, there is no city anymore. By estimate of the mayor's office, 30% of buildings are totally destroyed and 50% are heavily damaged. My house is burned to the ground."

Lyse Doucet
Chief International Correspondent

Image source, Getty Images

Moves towards peace talks in this conflict are so important, but also very difficult.

The Ukrainian flag is flying higher than ever now because of the invasion of the country. I was in the central square in Kyiv yesterday and the most popular rock star in Ukraine suddenly burst into the national anthem.

The flag is draped over coffins, the flag is on shirts and the flag is flying in capitals around the world. And that's the background to this moment where Ukrainians hope there will be a movement towards peace.

Last night President Zelensky said it "is time to meet, it is time to speak". And its very interesting that he says "I want to be heard by everyone, especially in Moscow" throughout this war, knowing that people in Russia aren't hearing the full story because of new media laws and repression, that he speaks to them directly.

One thing that has come out of talks with mediators like Turkey is that President Putin has agreed to meet Zelensky.

But Putin said yesterday - in his first public appearance since the invasion began a month ago - that "we know what we have to do next and we will definitely carry out all the plans we have made".

The biggest question before the invasion, and still to this day, is what is Putin's plan for Ukraine? Especially now, after Russia has incurred so many losses and his plan is not going as hoped.

We do know that the minimum is that he's got to provide security for people in eastern Ukraine, which he recognises as independent statelets, and for Crimea.

On the ground, he isn't there yet, so he isn't ready to call it a day.

In his video message, Ukraine's President Zelensky says he has "offered solutions for peace" since before the Russian invasion began.

Image source, Reuters

A spokesperson for Russia's defence ministry has said that Moscow has destroyed an underground depot in western Ukraine using hypersonic missiles.

Igor Konashenkov claimed that the warehouse had been housing missiles and "aviation ammunition of Ukrainian troops".

Russia has never before admitted to using hypersonic missiles in combat.

They are cutting edge ballistic missiles that can fly in the upper atmosphere at more than five times the speed of sound.

According to the Russian military, the "Kinzhal" missile system used in the strike is capable of hitting targets at a range of more than 2,000km (1,242 miles) and can overcome all existing air and missile defence systems.

Image source, EPA

Since Russian troops invaded Ukraine on 24 February, several rounds of negotiations have taken place between delegates from Kyiv and Moscow.

It's hard to gauge how much progress has been made in discussions so far.

Earlier this week, the Financial Times revealed a potential 15-point peace plan which would include Kyiv renouncing its ambitions to join Nato and promising not to host foreign military bases or weaponry in exchange for Western protection.

And Russia's top negotiator said Friday that Moscow and Kyiv had brought their positions "as close as possible" on a proposal for Ukraine to become a neutral state.

But Ukrainians have been more downbeat in their assessment of the state of talks. Mikhailo Podolyak, an advisor to President Volodymyr Zelensky who is taking part in the negotiations, said his country's position had not budged.

"Negotiation status. The statements of the Russian side are only their requesting positions," he wrote on Twitter.

And former Russian prime minister, Mikhail Kasyanov, told the BBC on Friday that President Vladimir Putin was not "serious" about peace talks and was unlikely to offer any solution to the conflict "that will be comfortable for Ukrainian people".

James Waterhouse
Kyiv correspondent, BBC News

The fear from Western officials had long been that the level of Ukrainian resistance in the besieged port city of Mariupol was finally softening.

Two days ago we had the prediction that it could fall within weeks, now we have reports of fighting within the city, where Russian troops have been able to work their way in through armoured columns.

Fighting is continuing to break out, while 300,000 people are still trapped there, caught under the shelling where evacuation routes still can't be used.

We understand that hundreds are still trapped in that bombed theatre that was thought to be housing more than 1,000 people, after it was targeted a couple of days ago.

The situation continues to be desperate and should Mariupol fall, it would provide Russia with an effective land corridor stretching for most of the south coast and up the eastern regions of Ukraine.

So it is strategically significant. But the thought from Western officials is that Russian forces are spreading themselves quite thin, soldier-wise on the ground.

The eastern city of Kharkiv is continuing to repel Russian attacks, the same in Sumy to the north-east, and the Kremlin is getting frustrated.

Mariupol though, as ever, is bearing the brunt.

Image source, Getty Images

More now on calls from Ukrainian President Volodymyr Zelensky for direct negotiations with Russian leader Vladimir Putin, which he made in comments posted in a video message overnight.

Speaking from Kyiv, Zelensky told Putin it was "time to meet, time to speak. I want to be heard by everyone, especially in Moscow”.

The Ukrainian leader told Russian officials that the time had come "for renewing territorial integrity and fairness for Ukraine".

Zelensky also accused Russian troops of causing a "humanitarian disaster" by blocking the port city of Mariupol, preventing supplies from reaching residents and shelling residential areas.

He alleged that Moscow had ordered its troops to "do everything, so the humanitarian catastrophe in Ukrainian cities turned into reason for Ukrainians to work together with the occupiers". He added that such actions amount to "a war crime".

Jonathan Beale
BBC defence correspondent

Image source, Getty Images

Russia has one of the largest and most powerful armed forces in the world, but that has not been apparent in its initial invasion of Ukraine.

Many military analysts in the West have been surprised by its performance on the battlefield so far, with one describing it as "dismal".

Its military advances appear to have largely stalled and some now question whether it can recover from the losses it has suffered.

This week, a senior Nato military official told the BBC: "The Russians clearly have not achieved their goals and probably will not at the end of the day".

So what has gone wrong? I have spoken to senior Western military officers and intelligence officials, about the mistakes Russia has made.

The Kremlin's first mistake - to underestimate the strength of resistance and the capabilities of Ukraine's own smaller armed forces.

• Read Jonathan's full analysis here

If you're just joining us, here's all you need to know to get you up to speed:

• Ukrainian President Volodymyr Zelensky has called for meaningful peace and security talks "without delay" with Moscow. He said this would be the only chance for Russia to limit damage from its "mistakes"

• Russian forces have agreed to allow residents to evacuate several towns and cities in Ukraine's eastern Luhansk after 09:00 local time (07:00 GMT), the region's governor said
• Ukraine claimed a Russian lieutenant general was killed in Chernobayevka after an artillery strike. The country's armed forces also said its air defences had destroyed at least 12 Russian air targets
• Former British PM Gordon Brown is among 140 academics, lawyers and politicians to sign a petition calling for Nuremberg-style trial for Putin. This was a legal system that tried Nazi war criminals after World War Two
• Former US Presidents Bill Clinton and George W Bush visited a Ukrainian church in Chicago to extend solidarity

This is Yvette Tan in Singapore signing off and handing over to my colleagues Mal Siret and Matt Murphy in London.

The UK Ministry of Defence has this morning posted an intelligence update on the situation in Ukraine, warning that a change in Russian tactics could result in more civilian deaths.

"The Kremlin has so far failed to achieve its original objectives," the ministry posted on Twitter, adding that Russia had been "surprised by the scale and ferocity of Ukrainian Resistance".

"Russia has been forced to change its operational approach and is now pursuing a strategy of attrition", it says.

"This is likely to involve the indiscriminate use of firepower resulting in increased civilian casualties, destruction of Ukrainian infrastructure, and intensify the humanitarian crisis."

Image source, Getty Images

The governor of Ukraine's eastern Luhansk region has said that an evacuations corridor will be opened later on Saturday.

In a post on Telegram, Serhiy Gaiday said Russian forces have agreed to allow residents to evacuate several towns and cities in the region after 09:00 local time (07:00 GMT), though he did not say where the people will be sent.

"The Russians continue the chaotic irregular artillery shelling of our cities," Gaiday wrote.

"However, we are waiting until 9 am, when the 'silence regime' should be established, to begin the evacuation of the region's residents, to bring food, water and medicine to those who remain."

"The humanitarian corridor has been agreed at a high level. I hope that the agreements reached by the Russians will be respected," he added.