Ukraine's industrial Donbas region, the focus of recent Russian offensives, has been destroyed, President Volodymyr Zelenskiy said as some of the world's richest countries pledged to bolster Kyiv with billions of dollars.

Since turning away from Ukraine's capital, Russia is using massed artillery and armour to try to capture more territory in the Donbas, comprised of the Donetsk and Luhansk areas, which Moscow claims on behalf of separatists.

"The occupiers are trying to exert even more pressure. It is hell there - and that is not an exaggeration," Zelenskiy said in a late Thursday address.

"(There are) constant strikes on the Odesa region, on the cities of central Ukraine. The Donbas is completely destroyed," he said.

Moscow calls its invasion a "special military operation" to rid Ukraine of fascists, an assertion Kyiv and its Western allies say is a baseless pretext for an unprovoked war.

As the invasion nears the three-month mark, the U.S. Senate overwhelmingly approved nearly $40 billion in new aid for Ukraine, by far the largest U.S. aid package to date.

The Group of Seven rich nations also agreed to provide Ukraine with $18.4 billion. Ukraine said the money would speed up victory over Russia and was just as important as "the weapons you provide".

U.S. Treasury Secretary Janet Yellen told reporters: "The message was, 'We stand behind Ukraine. We're going to pull together with the resources that they need to get through this.'"

The White House is working to put advanced anti-ship missiles in the hands of Ukrainian fighters to help defeat Russia's naval blockade, officials said.

U.S. Secretary of State Antony Blinken accused Russia of using food as a weapon by holding "hostage" supplies for not just Ukrainians, but also millions around the world.

The war has caused global prices for grains, cooking oils, fuel and fertiliser to soar.

In a further sign of Western action hurting the Russian economy, five foreign vice-presidents of Russia's Rosneft have resigned because of EU sanctions forbidding European citizens or Russians living in the EU to work at the oil company, sources said.

The EU said it is looking into ways of using the frozen assets of Russian oligarchs to fund the reconstruction of Ukraine, while the United States has not ruled out possibly placing sanctions on countries that purchase Russian oil.

NATO DIVISION

But divisions within NATO have also been on show with Turkey opposed to Sweden and Finland joining the alliance, a move that would reverse generations of military non-alignment in the biggest European security shake-up in decades.

Ankara accuses the two Nordic states of harbouring Kurdish militants, but U.S. President Joe Biden and European leaders said they were confident Turkey's concerns could be addressed.

Biden, hosting Swedish Prime Minister Magdalena Andersson and Finnish President Sauli Niinisto at the White House, told reporters: "I think we're going to be OK."

Niinisto said Finland would commit to Turkey's security, adding: "We condemn terrorism in all its forms and we are actively engaged in combating it."

The past week has seen Russia secure its biggest victory since the invasion began, with Kyiv announcing it had ordered its garrison in a steelworks in Mariupol to stand down, after a protracted siege.

Russian forces have, however, been pushed back this month from the outskirts of the second-largest city Kharkiv. Ukraine says it has recaptured 23 settlements near Kharkiv in the last two weeks.

In Mariupol, the ultimate outcome of the bloodiest battle in Europe for decades has remained unclear, with uncertainty over the fate of hundreds of Ukrainian defenders.

Moscow said on Thursday that 1,730 Ukrainian fighters had surrendered so far, including 771 in the past 24 hours.

Ukrainian officials, who have sought a prisoner swap, had declined to comment, saying it could endanger rescue efforts.

Late on Thursday, Sviatoslav Palamar, deputy head of the Azov Regiment defending the steelworks, released an 18-second video in which he said he and other commanders were still on the territory of the plant.

"A certain operation is going on, the details of which I will not disclose," he said.

The Switzerland-based International Committee of the Red Cross said it has registered hundreds of prisoners from the plant now held by Russia, but it has not given a precise number.

The leader of Russian-backed separatists in control of the area said nearly half of the fighters remained inside the steelworks.

The wounded were given medical treatment while those who were fit were taken to a penal colony and were being treated well, he said.

Reuters