Russia must stop "nuclear sabre-rattling," Nato's Stoltenberg says, in response to a question from a reporter, describing Russia's comments on the use of such weapons as "dangerous and irresponsible".

He says he has a clear message for Russia - that nuclear war cannot be won and should never be fought.

A Kremlin spokesman has said Russia could use nuclear weapons if it faced "an existential threat".

Image source, EPA

Nato members face a fundamentally changed security environment where authoritarian governments are prepared to use force, Mr Stoltenberg says.

"I expect we will address the role of China in this crisis," the Nato secretary-general goes on to say.

China has provided Russia with political support including by spreading "blatant lies and misinformation," he says.

To Brussels now, where Nato's Secretary General Jens Stoltenberg is speaking to reporters ahead of US President Joe Biden's visit for talks with fellow leaders of the military alliance.

Stoltenberg says Russia's invasion of Ukraine is brutal, and the human suffering is terrible to watch.

"We are determined to do all we can to support Ukraine," Stoltenberg says, but Nato has a "responsibility" to ensure the war does not escalate beyond Ukraine, he adds.

Image source, Reuters

Russia's foreign minister, Sergei Lavrov, has said Moscow has the "spirit and will to defend Russian culture in Ukraine", in a televised speech to students at the Moscow State Institute of International Relations.

As we have been reporting, the Kremlin's narrative, delivered through pro-government media, is that troops are fighting Nazis and fascists and defending the motherland.

Lavrov also said talks between the two sides were "difficult" because Ukraine "constantly changes its position".

And he was critical of suggestions from Poland that a peacekeeping mission be set up in Ukraine.

"This will be the direct clash between the Russian and Nato armed forces that everyone has not only tried to avoid but said should not take place in principle," he said.

Turning now to the north-eastern city of Sumy. A member of the city council there has told the BBC that approximately 100,000 residents have left.

"Our city is almost surrounded, we have one exit to Poltava through which women and children leave and medical supplies are brought," Andrii Baranov said.

There is a shortage of medical supplies and fuel in the city he added.

Baranov estimated that Ukraine could hold the city for another three or four weeks.

"We strongly need a no-fly zone," he said.

Baranov added that the situation in Sumy was nowhere near as bad as in Mariupol in the south-east - in Sumy only around 10 houses have been destroyed.

Sumy's critical infrastructure has been bombed but not civilians' houses, he said.

Image source, PA Media

We're getting some details now of a UK government cabinet meeting that was held this morning.

The prime minster told his colleagues that allies should go further in providing more defensive military aid to Ukraine.

A No 10 spokesperson says: "The prime minister paid tribute to the fierce resistance from the Ukrainian people in the face of the brutal and inhumane actions of Putin's regime.

"He said Putin's actions had already crossed the threshold of barbarism and the west should not hesitate to go further in strengthening sanctions and providing further defensive military aid to Ukraine."

Image source, Reuters

In the UK, Prime Minister Boris Johnson is facing questions from MPs in the House of Commons.

Conservative MP Sir Oliver Heald says people across his constituency of north east Hertfordshire are coming together "to provide support and refuge to families fleeing the invasion in Ukraine".

He says it demonstrates the "open-hearted generosity of the British people" and asks the PM if he will work with the refugees minister to make the process as simple and speedy as possible.

Johnson thanks all those involved in the UK's two big schemes to welcome people from Ukraine.

He says the Homes for Ukraine scheme is now open and says thousands of people have applied calling it a "fantastic thing".

Dan Johnson
BBC News

There is growing anxiety in Poland over Russia's invasion of Ukraine, and people have started taking action.

At an army base on the edge of Krakow, I saw a new generation of recruits signing up for the Polish Territorial Defence Forces.

Many here don't think President Vladimir Putin's military attacks will end in Ukraine.

Factory worker Patrycja, 26, says she doesn't want to feel helpless if something happens in Poland. She says she's willing to defend the country and isn't afraid.

Paweł Kwieciński, an ex-soldier turned builder who has come back to volunteer, says: "Our home is our fortress. We have to fight for it. It's our duty."

Across Poland, applications are up seven-fold and the government has announced an increase in defence spending.

Brigade Cdr Col Marcin Siudziński this morning received 150 new recruits and wants to welcome more. He says he's seen a surge in patriotism fuelled by what's happening across the border.

Adam Easton
Warsaw Correspondent

Poland has decided to expel 45 Russian diplomats suspected of spying against the country, a Polish foreign ministry spokesman said.

The 45 Russians are either suspected being spies or are associates of spies, Stanislaw Zaryn, a spokesman for Polish special services said earlier.

One of them was identified during an investigation into a Polish citizen, who worked in the archive of Warsaw's civil records office, for alleged espionage, Mr Zaryn said.

The Pole was arrested last week and has been remanded in custody for three months.

Russia’s ambassador to Poland, Sergey Andreyev, denied the allegations after he was summoned to the Polish foreign ministry earlier on Wednesday.

Mr Zaryn wrote on Twitter the Russian ambassador repeated "absurd lies" adding, he is "one big fake".

Laura Bicker
BBC Seoul Correspondent

Image source, Reuters

President Zelensky used his live video address to the Japanese parliament to warn of the dangers his country faced from Russian attacks on nuclear plants - and he raised concerns over the site of the Chernobyl meltdown.

Earlier this month, Russian soldiers entered the 32km (19 mile) Chernobyl exclusion zone and surrounded the perimeter of the nuclear power plant.

Moscow said it had secured the site jointly with the Ukrainian national guard, but Ukraine said Russian troops had taken full control.

Zelensky's speech will have resonated with Japanese lawmakers, who remain haunted by the Fukushima nuclear disaster in 2011.

The Ukrainian leader also called for sanctions to continue to try to build international pressure to end Russian aggression and said the fighting in some areas of his country was so bad that people were unable to bury relatives who had been killed.

Image source, EPA

Ukrainian President Volodymyr Zelensky has called on Japan to increase sanctions on Moscow, including by introducing a trade embargo on Russian goods.

In a video address to the Japanese parliament in Tokyo, Zelensky praised Japan for leading the way in Asia by piling pressure on Russia.

Japan has joined other Western countries in imposing sanctions on Russian banks, businesses and individuals.

Without providing evidence, Ukraine's president said Russian forces were preparing new attacks from the exclusion zone around the defunct Chernobyl nuclear power station. He also said he had received reports that Russia could be preparing to use chemical weapons.

Zelenksy, who has also addressed other parliaments around the world virtually, including in the UK, received a standing ovation from the packed room after his speech.

Image source, Reuters

As we've been reporting, the US Pentagon says there are signs Ukrainian forces are fighting back successfully in some areas. The situation on the ground remains fluid, but here is the latest we know.

The Ukrainian Defence Ministry says Ukraine's forces have retaken Makariv, which is a town about 40 miles west of Kyiv.

Ukrainian flags are flying there once more, according to local authorities.

Russian forces were pushed back in the farming town of Voznesensk, where a combination of volunteers and Ukrainian troops delivered a blow to Russian plans.

First they blew up the bridge and then they manage to drive the invading army back, up to 100km, to the east.

Meanwhile, in Kherson, close to the Crimean peninsula and the first city to fall to Russia, Ukrainian forces are also trying to recapture territory.

Image source, EPA

We reported earlier that German Chancellor Olaf Scholz said Russia's invasion of Ukraine was "stuck" and that President Vladimir Putin needed to "hear the truth".

He also warned that suggestions of an instant embargo on Russian energy supplies should be dismissed as the impact on Europe would be devastating.

He said Germany was in the process of becoming independent from Russian energy sources, but "that doing this from one day to the next would push our country and the whole of Europe into a recession".

He warned that "entire industries would be on the brink [of collapse]" and that existing anti-Russian sanctions were already hitting German citizens hard.

Steve Rosenberg
BBC Russia editor

The Kremlin refuses to call its offensive in Ukraine a war and Russian media outlets have been told not to call it an "invasion".

But today's Russian papers speak of "battles near Kyiv" and talk of "the front line". There are photos of tanks and soldiers that Moscow presents as "heroes".

Pro-government media in Russia want the public to think that what the country's troops are doing now in Ukraine is similar to what the Red Army did in World War Two; fighting Nazis and fascists and defending the motherland - it's part of the Kremlin's attempt to create an alternative reality around events there.

Meanwhile, the editor-in-chief of the independent Novaya Gazeta newspaper, Dmitry Muratov, has decided to auction off his Nobel Peace Prize medal to raise money for Ukrainian refugees.

Image source, EPA

We've been reporting on statements from Ukrainian authorities that their forces have been regaining territory from the Russians.

A spokesman for the US Defence Department, John Kirby, told reporters at the latest briefing that Ukraine has been defending parts of the country "very smartly, very nimbly, very creatively".

"We have seen indications that the Ukrainians are going a bit more on the offensive now," he said.

"We have seen them now in places, particularly in the south near Kherson, [where] they have tried to regain territory."

Kirby said Ukrainian forces had been planning counter-attacks and were now "moving in that direction".

"The Ukrainians are putting up a very stiff defence... the Russians have not achieved any of the strategic objectives that they set out to - or certainly not without loss."

General Sir Adrian Bradshaw, a former Nato deputy supreme allied commander, has been telling BBC Radio 4 Today's programme that the Ukrainians are "continuing to display incredible courage and are holding the Russians in many places".

While Russian forces have made significant gains in the south, he says it seems unlikely they will stop without having taken Mariupol and securing the land link to Crimea.

Bradshaw's assessment is that Putin will very much want to try see a change of government. He adds it remains to be seen what sort of equilibrium he will be prepared to accept as a basis for stopping the actual fighting.

He says it seems pretty likely that Putin will continue to double down on his efforts to obtain his objectives so that he can go back to the Russia people with something he can call a victory.

Bradshaw says Nato is on notice from Putin that its nations, particularly those that were former Soviet republics, are in his sights and believes Nato will have to show strength, unity and resolve at Thursday's emergency summit in Brussels.

He also suggests Nato's European nations will have to foot the bill for proper deterrence in Europe.

Steve Gordon, a humanitarian response adviser for the charity Mercy Corps, has just left the north-eastern city of Kharkiv. He's been telling BBC Radio 4's Today programme that people have become "more and more dependent on aid".

"We haven't yet seen the international aid effort kick in," he says.

Gordon adds that normal systems - like large scale food shipments from UN agencies and other international organisations - aren't yet available and everybody is scrambling to get things going.

He says the aid operation is being led by municipalities and small organisations on the ground.

Gordon witnessed church groups distributing items, using the church as a warehouse, and queues of people coming all day.

He says there's a Hare Krishna temple in Kharhiv where they have started cooking and feeding up to 1,000 people a day.

Gordon says food supplies are getting through using the railway lines, but fears what would happen if these communities were cut off by Russian forces.

Russian forces are failing to advance in Ukraine despite the continued heavy bombardment of cities and towns, German Chancellor Olaf Scholz says.

"Putin's offensive is stuck despite all the destruction that it is bringing day after day," he tells politicians in Germany, adding that the Russian leader "needs to hear the truth", stop the fighting and try to find a diplomatic solution.

The war, Scholz says, is not just destroying Ukraine, "but also Russia's future".

Warning Moscow of further penalties, he says: "We are constantly tightening the sanctions, but [the measures] should not hurt European states harder than the Russian leadership."

He says Ukrainians can "rely on Germany" and that "refugees are welcome with us".

Lyse Doucet
Chief International Correspondent, Kyiv

At 05:00 GMT, 07:00 local time, residents cautiously emerged from mostly being underground in basements or bunkers.

They emerged to possibly one of the noisiest mornings since the start of this invasion – to the sound of more sustained heavy artillery. It seemed to come from the north-west, a constant rattle of small arms fire for more than half an hour.

And it seems to be closer. We're getting reports the Russian army is shelling two districts in the north-west of Kyiv. The initial reports are that private houses, residential apartment blocks and a mall are damaged.

So late last night the narrative was that the Ukrainian forces were counter-attacking, that they’d raised the flag in Makariv, which is about 40 miles west of Kyiv.

We heard from London and Washington that the advance on the capital, which is still regarded as one of President Putin's aims, had been stalled again. And then you wake up and you hear something different.

This is the reality of the war that began fought on multiple fronts for the past month. The battlefield and the narrative keep shifting and some days it's in very small steps, and some days it's in big sweeps.

Image source, Getty Images

The strategically important port city of Mariupol, in southern Ukraine, has become the most heavily bombed since the start of the invasion.

Pavol, who managed to leave Mariupol three weeks ago, is now part of a group which runs supplies into the city and helps people to get out.

He’s been telling BBC Radio 4’s Today programme that his team helped evacuate 96 people from the city yesterday.

During the operation he says one of their vehicles was destroyed when Russian forces started shelling - although luckily there were no passengers in it and the driver managed to get out.

Pavol's parents managed to escape from Mariupol separately a few days ago. He says his mum got caught up in a battle between Russian and Ukrainian tanks but managed to squeeze between them before they exchanged fire.

He says his dad had no fuel but was near a fire station that came under shelling. He managed to get some petrol from a fire engine and escape. They are both now in Chernobyl in northern Ukraine.