Russia claims Mariupol 'liberated,' US rushes new aid for Ukraine

Russian President Vladimir Putin on Thursday claimed the "liberation" of the flattened city of Mariupol after nearly two months of fighting, demanding its trapped Ukrainian defenders be sealed into their underground last stand.

The fate of the besieged port has become totemic as Russia battles to complete a land bridge covering territories already under its control, including Crimea -- which would deprive Ukraine of its industrial heartland and most of its coastline.

President Joe Biden, however, said Putin was doomed to failure, announcing $800 million (740 million euros) in extra US military aid including howitzers and tactical drones.

"Our unity at home with our allies and partners, and our unity with the Ukrainian people, is sending an unmistakable message to Putin -- he will never succeed in dominating and occupying all of Ukraine," he said.

Ukraine appealed for an immediate humanitarian corridor to allow civilians and wounded fighters to be evacuated from Mariupol's sprawling Azovstal steel plant.

"They have almost no food, water, essential medicine," Ukraine's foreign ministry said.

Three school buses filled with Mariupol evacuees including women and children arrived in the city of Zaporizhzhia after crossing through territory held by Russian forces.

Exhausted evacuee Valentina, 73, said she urgently needed medication for her back as she struggled to remain standing.

"My apartment has been destroyed just like the house of my son," she said, still wearing her slippers along with a torn black coat.

"From day one we were in a basement. It was cold. We were praying to God. I was asking him to protect us."

The flow of Western military aid has helped force Russia to deflect it's offensive to eastern Ukraine and accentuated the pressure on places like Mariupol on the shores of the Sea of Azov.

"Mariupol has been liberated," Russian Defence Minister Sergei Shoigu told Putin during a televised meeting. "The remaining nationalist formations took refuge in the industrial zone of the Azovstal plant."

Shoigu said around 2,000 Ukrainian soldiers remained inside the site, where the last pocket of resistance has been sheltering in a network of tunnels. 

Up to 2,000 civilians are also enduring terrible conditions as they seek refuge inside the plant, according to Ukrainian authorities.

Putin said the "liberation" of Mariupol was a "success" for Russian forces but ordered Shoigu to call off the planned storming of the plant.