Image source, Reuters

Continuing, Guterres has criticised his own organisation's security council for failing to prevent or end the war in Ukraine.

He says: "Let me be very clear: the security council failed to do everything in its power to prevent and end this war, and this is a source of great disappointment, frustration and anger. But the men and women of the United Nations are working every day for the people of Ukraine, side by side, with so many brave Ukrainian organisations."

He says he's had "intense discussions" with President Zelensky to make an evacuation from Mariupol a reality.

UN Secretary General Antonio Guterres is now speaking, following a meeting with Ukrainian President Volodymyr Zelensky.

He says the situation in the besieged southern port city of Mariupol is a "crisis within a crisis".

"We are doing everything possible to evacuate people from Mariupol's Azovstal" steel works, he says.

But he tells reporters he won't "enter into any comment that could undermine that possibility".

We'll bring you more updates on the talks as we have them.

Image source, Handout

As we've been reporting, a British national has been killed in Ukraine and a second is missing, the UK's Foreign Office has said.

The BBC has been told the man who was killed is Scott Sibley. He's understood to have been fighting for Ukrainian forces.

The Foreign Office has not confirmed the identity of either person but has said it is supporting their families.

Details of Sibley's death and how or when the second person went missing have also not been given.

Read more.

Sarah Smith
North America Editor

Image source, EPA

President Biden is asking Congress to authorise an enormous sum of money for Ukraine – $33bn. More than twice as much as the US has already spent on providing military equipment and humanitarian aid.

The US president wants to show he is undeterred by vague threats about the possible use of nuclear weapons and a warning from Vladimir Putin that there could be retaliatory strikes against countries that intervene in Ukraine.

He shrugged off those comments saying they show the desperation Russia is feeling about their abject failure to do what they set out to do.

The proposal includes $20bn in military assistance to Ukraine, $8.5bn in economic support and $3bn for humanitarian aid. As well as money to help with global food shortages caused by the war.

Explaining to Americans why this money is needed at a time when many are suffering from rising living costs he said: "The cost of this fight is not cheap, but caving to aggression is going to be more costly."

An additional plan to allow US authorities to not just freeze but liquidate the assets of Russian oligarchs is bold – it has raised concerns among civil liberties groups in America. But is likely to gain bi-partisan support in the US congress.

It will not begin to cover the cost of the additional sums of money the White House wants to spend supporting Ukraine's war efforts.

More now on news that a UK national has been killed and another Briton is missing in Ukraine.

The Foreign Office has provided no details of what the pair were doing in Ukraine in its statement.

The government had urged British nationals to leave Ukraine in February and, after Russia invaded, advised against all travel, external to the country.

In the early days of the war, Foreign Secretary Liz Truss said she supported individuals from the UK who might want to go to Ukraine to fight but the government later advised against this.

Also in the Q&A session, Biden says that in an effort to aid Poland and Bulgaria - after Russia cut off gas supplies to them yesterday - the US will work with allies and may divert the sale of natural gas to them.

He says: "Poland indicated significant reserves of gas, as does Bulgaria, but not as much.

"We've worked with allies from Japan, and may divert the sale of natural gas from those countries to Poland and Bulgaria.

"That's all I can say right now."

The press conference has now ended. We'll wait to see how the Kremlin responds to what Biden has outlined.

After finishing his speech, Biden takes questions from reporters.

He is asked about whether the US is now in a "proxy war" with Russia and how concerned he is about how the Kremlin might respond.

Biden says "we're prepared for whatever they do".

Russia has repeatedly suggested that the West's support of Ukraine - particularly with military aid - amounts to a proxy war.

"Aggression will not win, threats will not win," Biden adds.

He says the war in Ukraine has presented a serious problem but also an enormous opportunity to deter future wars.

"All these actions are about the truth - investing in Ukraine's freedom and security is a small price to pay to punish Russia's aggression to lessen the risk for future conflict."

He finishes with an "unmistakable message to Putin: You will never succeed in dominating Ukraine".

Responding to Russia's comments about the possibility of the Ukraine war escalating into a nuclear conflict if the West continues supporting Kyiv, US President Joe Biden says it is "a reflection of Russia's failure".

Biden says Russia's comments concern him "because it shows Russia's desperation".

But, the US president adds: "No one should be making idle comments about use of nuclear weapons."

On Wednesday, President Putin said western powers intervening in Ukraine would face a "lightning-fast response".

Russia, he said had "all the tools for this, that no one else can boast of having". He added: "we'll use them, if needed. And I want everyone to know that".

Also speaking on Wednesday, Russian Foreign Secretary Sergei Lavrov warned that the risk of a nuclear war is "very serious now" and they shouldn't be underestimated.

Image source, Reuters

Biden says that despite Russia's claims to be a reliable source of energy for the world, "their actions towards Poland and Bulgaria show otherwise".

He is referring to yesterday's announcement that Russian energy giant Gazprom has cut off gas to both countries.

This, Biden says, shows Russia is using energy "not just as a commodity, but a weapon".

"We will not let Russia intimidate and blackmail their way out of those sanctions", he adds.

Biden says the US has sent more than 50 million rounds of ammunition to Ukraine, as well as providing 10 anti-armoured systems for every Russian tank in Ukraine.

He says the White House has almost exhausted the "draw down" authority that Congress authorised for Ukraine last month.

Explaining his proposal for Congress, Biden says: "Basically we're out of money - that’s why today, in order to sustain Ukraine, I'm sending congress a supplemental budget request to keep weapons and ammunition flowing to Ukraine and continue the delivery of economic and humanitarian assistance.

"This funding addresses the needs of military in critical months ahead and begins transition to longer term security symptoms to deter Russian aggression."

Biden says more funding is needed to ensure food security in Ukraine is restored.

He urges Congress to pass the new bill as soon as possible to ensure that grain exports are restored.

Biden adds that this will help restore food security for both Americans and Ukrainians. He says it'll help ease rising food prices as well.

Biden says it is "thanks to the aid we've provided that Russian forces have had to retreat from Kyiv".

But the US president warns that this does not mean the Russian army won't return.

That's why, he says, the additional military and financial aid is important for Ukraine.

President Biden says the US is not attacking Russia but instead helping Ukraine defend itself against Russian aggression.

"Just as Putin made the choice to begin this brutal invasion, he could make the choice to end it," he says.

"Russia is the aggressor and the world must, and will hold, Russia accountable."

He says the Russian invasion is yielding immense human cost in the horrifying evidence of atrocities and war crimes in areas they try to control.

Biden is now setting out his plans at the White House.

He says it is critical the additional $33bn (£27bn) in funding he is proposing gets approved by Congress as soon as possible.

Biden says backing Ukraine is "not cheap" but the US can't "stand by".

US President Joe Biden is at the podium at the White House and is outlining his plans to offer more support to Ukraine.

He will ask Congress for $33bn (£27bn) in military, economic and humanitarian assistance to support Ukraine "for the next five months".

The package includes more than $20bn in military aid, $8.5bn in economic aid and $3bn in humanitarian aid.

We'll be bringing you live updates.

Image source, Reuters

Daniel Thomas
Business reporter, BBC News

Image source, Getty Images

One of Germany's biggest energy firms has said it is preparing to buy Russian gas using a payment system that critics say undermines EU sanctions.

Uniper says it will pay in euros which will be converted into roubles, meeting a Kremlin demand for all transactions to be made in the Russian currency.

Other European energy firms are reportedly preparing to do the same amid concerns about supply cuts.

Uniper said it had no choice but said it was still abiding by EU sanctions.

The European Commission said last week that if buyers of Russian gas could complete payments in euros and get confirmation of this before any conversion into roubles took place, that would not breach sanctions.

Read more here.

A British national has been killed in Ukraine and a second is missing, the Foreign Office has said.

The Foreign Office has not said whether they were fighting in Ukraine.

A Foreign Office spokesman said: "We can confirm that a British national has been killed in Ukraine and are supporting their family."

On the missing person, they added: "We are aware of a British national who is missing in Ukraine and are supporting their family. We are urgently seeking further information."

Read more here.

A Ukrainian presidential aide says the world recognises that his country has the right to defend itself by carrying out attacks, external on Russian military bases and warehouses.

"Russia has attacked and [is] killing civilians. Ukraine will defend itself in any way, including strikes on the warehouses and bases of the killers," Mykhailo Podolyak wrote on Twitter.

"The world recognizes this right."

Russia denies targeting civilians in what it calls its "special military" operation in Ukraine.

Earlier, Russia's foreign ministry spokeswoman Maria Zakharova warned the West against encouraging Ukraine to attack inside Russian territory.

Further "provocation" would be met with a "harsh response", she said.

Image source, Reuters

German Chancellor Olaf Scholz says Germany will provide Ukraine with training on how to use howtizers - a type of artillery weapon - sent by the US.

There had already been a major policy shift in Berlin, with Germany previously authorising the supply of 50 anti-aircraft tanks to Ukraine.

Germany has long had a policy of not supplying heavy weaponry to conflict zones and its decision surprised the world.

Scholz is currently in Tokyo, Japan, seeking closer ties with countries that share its democratic values in the Asia-Pacific region.