Earlier, the wives of two Ukrainian fighters still holed up in Mariupol's Azovstal steelworks begged Pope Francis to help them.

Kateryna Prokopenko and Yuliya Fedosiuk spoke to the Pope in the Vatican's St Peter's Square. In a video released by the Vatican, they tearfully ask Pope Francis to help their husbands, saying: "Please don't let them die."

They tell him the remaining soldiers have no food or water, many are injured and some are dead. They said the troops are waiting to be evacuated to a third country.

The Pope said he would do everything possible and will pray for them.

Image source, REUTERS/Alexander Ermochenko

Seriously injured defenders of the Azovstal steel plant in the devastated port city of Mariupol could be swapped with Russian prisoners of war, Ukraine's Deputy Prime Minister Iryna Vereshchuk has suggested.

"There is no agreement yet" and "negotiations are continuing," Vereshchuk has said in a Telegram post.

She says the government has been working on different options to rescue fighters trapped in the Azovstal plant but "none of them are perfect".

The troops in the steelworks have insisted they will never surrender to the Russian forces surrounding them.

Image source, EPA

President Putin does not want a confrontation between Nato and his own forces, the US defence secretary has said.

"This is a fight that he really doesn't want to have," Lloyd Austin told a congressional hearing, according to the Reuters news agency.

Austin explained that many Russian troops were tied up in Ukraine, and others were in Belarus - while Nato had some 1.9 million soldiers available.

His comments come as Sweden and Finland consider joining Nato.

A former prime minister of Finland told the BBC earlier he thought his country was 99.9% likely to sign up to the alliance, and said he expected an initial announcement tomorrow.

The situation in Kherson "is really awful", a woman who has relatives in the Russian-occupied region has told the BBC.

Speaking on BBC World News, Larisa Kruten said: "I'd characterise the situation in Kherson like silent terror."

Last week "my family were totally cut off from the communications" - including television, internet and phone services, she said.

We previously reported that pro-Kremlin authorities in Kherson will ask Vladimir Putin to make the region part of Russia, according to the Russian news agency Tass.

And the Ukrainian elected mayor for the region has responded saying: "I know for sure that the people of Kherson see themselves exclusively as part of Ukraine."

"No one has the right to quietly make such a fateful decision for them", Ihor Kolykhaiev said in a statement on Facebook.

Larisa, who was speaking from Odesa but is from Kherson, said the residents under occupation are being shown Russian news and some are starting to be "influenced" by propaganda.

She told the BBC Russian soldiers have "closed entry to the city" and her relatives are unable to leave.

Sarah Rainsford
Reporting from Kyiv

Image source, Reuters

Russia has given another strong hint that it plans to annex large parts of Ukraine – starting with Kherson in the south, which is already controlled by Russian forces.

A pro-Moscow official there, installed when elected leaders were removed at gunpoint, says Kherson will appeal to Vladimir Putin directly to incorporate the region into Russia.

The Kremlin spokesman said any such move would need what he called a clear "legal" basis. In Moscow-speak, that could mean holding a sham referendum to claim popular support.

Here in Kyiv, a senior official said Russian occupiers could ask to join Mars if they wanted - but Kherson would be liberated, in any case.

The Ukrainian military is making gains in fighting elsewhere: pushing Russian troops from territory to the north of Kharkiv.

But after losing ground in the east, Ukraine has now suspended use of a major pipeline there. It says fuel is being stolen from the Sokhranivka route – and diverted to Russian-backed forces.

But suspending the pipeline will cause significant disruption for gas supplies from Russia to Europe.

If you're just joining us, here are the main points from UK Prime Minister Boris Johnson's joint news conference with Finland's President Sauli Niinisto:

• The UK and Finland have signed a security declaration pledging mutual support if their militaries come under attack
• Johnson said the nature of the assistance in the event of a disaster or an attack would depend on the request of the other party
• As Finland considers whether to apply to join Nato, Niinisto said membership of the alliance would "not be against anybody" while Johnson stressed Nato is a defensive alliance and "poses no threat to anyone"
• Both men welcomed a closer partnership and increased cooperation
• When asked if Finland potentially joining Nato would provoke Russia, Niinisto said Russia's behaviour had changed the picture. His message to Putin was: "You caused this – look at the mirror"
• Earlier today Johnson and his Swedish counterpart signed a similar declaration between the UK and Sweden

Putin to blame if Nato expands, says Finlandpublished at 18:36 British Summer Time 11 May 2022

18:36 BST 11 May 2022

Katya Adler
Reporting from Helsinki

Image source, Getty Images

Finland says applying to join Nato is all about defence. But Vladimir Putin doesn’t see it that way. He’s always viewed Nato’s eastern expansion as a threat.

Finland shares an 800-mile (1300-kilometre) long border with Russia, bringing the alliance’s military might that much closer Moscow.

Finnish and Swedish membership will make Nato more robust too - boosting its eastern flank and presence in the Baltic Sea. And the Kremlin has threatened retaliation.

Some fear it might deploy targeted nuclear weapons. But Finnish diplomats I’ve spoken to believe Russia has its military hands full in Ukraine and that it will instead focus on cyber and disinformation campaigns.

They say President Putin has himself to blame for Nato expanding. Before Russia invaded Ukraine, most Finns and Swedes preferred to work alongside, but not inside, Nato.

Russia's aggression - its expansionist zeal - changed all that.

Boris Johnson is asked whether the UK is sending generous support to Ukraine but failing to support people struggling with the cost of living at home.

He says his aim is "to prevent further catastrophe", including economic consequences.

He warns that if Russian President Vladimir Putin is not resisted, the invasion of Ukraine would not be the end of his "neo-imperialist, revanchist ambitions".

Johnson says it's "so important we are together, strong now" to deter further Russian aggression.

Finnish President Sauli Niinisto was asked about whether his country joining Nato would provoke Russia.

He reminded the press conference that this was "not the first time we are discussing Nato".

"In the end of last year they [Russia] stated that Finland and Sweden can’t join Nato – they demanded that Nato doesn’t take new members," he says.

The Finish president said this changed the picture as Russia was stating that Finland and Sweden did not have their "own will", and the Russian invasion on 24 February also changes the picture.

"They are ready to attack their neighbouring country, so... my response would be that ‘you caused this – look at the mirror’," he says.

Image source, PA Media

Boris Johnson was asked about the UK's capability to deploy military aid after years of alleged under-investment.

He says the UK military is being increasingly deployed because of the UK's ability to make record investments in the armed forces.

Nato is a defensive alliance, he adds - it poses no threat to anyone, it's there for the purpose of mutual defence.

"We make these commitments to our friends in Finland not just because we can, but because we must."

Image source, Frank Augstein/PA Wire

Finland's President Sauli Niinistö is asked what the main difference is after signing this security agreement.

Niinistö responds by saying there is now a "clear bilateral agreement" between UK and Finland on how they will work together in future.

He also describes the agreement as a "big step forward" and says both countries will enhance co-operation with each other in different sectors.

Boris Johnson says the declaration the two leaders have signed today "ensures that our two nations can intensify our partnership and take it to unparalleled heights".

"From the high north and the Baltics beyond, our armed forces will train, operate, and exercise together, marrying our defence and security capabilities and formalising a pledge that we will always come to one another's aid," he says.

This co-operation increases Finnish security, President Niinisto says.

"This is a very, very good way to go forward and we do appreciate this big step which is now taken," he says.

Asked if there will be British boots on the ground if Finland asks for help during a possible conflict with Russia, Johnson says it depends.

"In the event of a disaster or an attack on either of us then yes we will come to each other's assistance including with military assistance," he says.

"But the nature of that assistance will depend upon the request of the other party."

That echoes similar statements he made in Sweden earlier today.

Image source, Pool

UK PM Boris Johnson says Russia's invasion of Ukraine has caused the "end of the post-Cold War period".

He also says the invasion has "rewritten our reality", "reshaped our future" and opened a new chapter.

Finnish President Sauli Niinisto says both countries have condemned the Russian war in Ukraine, and both have been helping Ukraine.

It's not a zero-sum game - where someone has to lose for another to win - he says. If Finland seeks to increase its security, that doesn't mean taking away from anyone else.

"Here in Finland we appreciate UK's strong support Nato's open-door policy and for potential Nato membership," the Finnish President says.

"That is very valuable to us."

Sauli Niinisto says joining Nato wouldn't be "against anybody", adding "we would like to maximise our security one way or another while thinking about membership in Nato".

Image source, Pool

Finnish President Sauli Niinisto begins by saying the UK and Finland are "great friends" and "strong security partners".

"We signed a joint statement - we will stand together and support each other in any circumstances, in good and bad weather."

Image source, POOL

UK Prime Minister Boris Johnson is starting his news conference in Finland, where he has been meeting Finnish President Sauli Niinisto as the country considers whether to join Nato.

The leaders have been discussing Europe's response to Russia's ongoing invasion of Ukraine.

Stay with us for full coverage of the event.

UK Prime Minister Boris Johnson is due to speak shortly after a meeting with Finnish President Sauli Niinisto about the war in Ukraine and European security.

He addressed a news conference earlier with Swedish Prime Minister Magdalena Andersson, after both countries agreed a new deal to come to each other's aid if either is attacked.

He is expected to sign a similar pact with Finland.