New surrender deadline in Mariupol as West promises Ukraine more arms

Russia gave Ukrainian fighters holding out in Mariupol a new ultimatum to surrender by Wednesday afternoon as it pushed for a decisive victory in its offensive in the east, while Western governments promised to give Ukraine more military help.

Thousands of Russian troops backed by artillery and rocket barrages were attempting to advance in what Ukrainian officials have called the Battle of the Donbas - a final push by Moscow to seize two eastern provinces it claims on behalf of separatists.

Russia's nearly eight-week-long invasion has failed to capture any of Ukraine's largest cities. Moscow was forced to retreat from northern Ukraine after an assault on Kyiv was repelled last month, but has poured troops back in for an assault on the east that began this week.

The biggest attack on a European state since 1945 has led to nearly 5 million people fleeing abroad and reduced cities to rubble.

In the ruins of Mariupol, site of the war's heaviest fighting and worst humanitarian catastrophe, Russia was hitting the last main Ukrainian stronghold, the Azovstal steel plant, with bunker-buster bombs, Kyiv said. Ukraine says hundreds of civilians are sheltering beneath the factory.

"The world watches the murder of children online and remains silent," presidential adviser Mykhailo Podolyak wrote on Twitter.

Russia has been trying to take full control of Mariupol since the war's first days. Its capture would be a big strategic prize, linking territory held by pro-Russian separatists in the east with the Crimea region that Moscow annexed in 2014.

But not a single Ukrainian soldier had laid down their weapons after an ultimatum to surrender lapsed on Tuesday, Russia's defence ministry said. It announced a new deadline of 2:00 pm on Wednesday (1100GMT) for defenders to lay down arms.

Ukraine has vowed never to surrender in Mariupol and its general staff said fighting was continuing at the plant.

Ukraine announced plans to send 90 buses to evacuate 6,000 civilians from Mariupol on Wednesday, saying it had reached a "preliminary agreement" with Russia on a safe corridor, the highest profile announcement of such a plan for weeks. Moscow has blocked all previous convoys to Mariupol, including one sent by the Red Cross at the end of March.

Civilians have been able to escape to other parts of Ukraine only in their own vehicles, while tens of thousands have been bussed to Russia in what Moscow calls humanitarian evacuation and Kyiv calls illegal forced deportation.

Once a prosperous port of 400,000 people, Mariupol has been turned into a blasted wasteland with corpses in the streets, and residents confined to cellars. Ukrainian officials say tens of thousands of civilians have died there.

BATTLE OF DONBAS

The battle for the Donbas region could be decisive as Russia searches for a victory to justify President Vladimir Putin's Feb 24 invasion.

British military intelligence said fighting in the Donbas was intensifying as Russian forces tried to break through Ukrainian lines and disrupt its reinforcements and that Russia was still building up forces on Ukraine's eastern border.

Moscow is hoping its advantage in firepower will give it more success against Ukrainian defenders than in the failed campaign against Kyiv, when its overstretched supply lines were attacked by nimble small units. Kyiv has recently attacked Russian supply lines near the eastern city of Kharkiv.

Russian forces captured Kreminna, a frontline town of 18,000 people, on Tuesday and Ukraine's general staff said Russian forces had attempted an offensive near Kharkiv, the country's second biggest city.

Inside Kharkiv, where at least four people were killed in missile strikes on Tuesday, the body of an elderly man lay face down near a park on a suburban street, a ribbon of blood running into the gutter.

"He worked in security not far from here," a resident named Maksym told Reuters. "The shelling began and everyone fled. Then we came out here, the old guy was already dead." Charles Michel, head of the European Council that groups the 27 EU member states, arrived in Kyiv as the latest European official to visit and demonstrate support.

The White House said new sanctions against Russia were being prepared and U.S. President Joe Biden is expected to announce a new military aid package about the same size as last week's $800 million one in the coming days, sources told Reuters.

The United States, Canada and Britain said they would send Ukraine more artillery, while Norway said it had shipped Ukraine 100 Mistral air defence missiles.

Russia has denied using banned weapons or targeting civilians and says, without evidence, that signs of atrocities were staged.

Video released by Ukraine's Azov battalion purported to show people living in a network beneath the sprawling Azovstal steel plant, where they say hundreds of women, children and elderly civilians are sheltering with supplies running out.

"We lost our home; we lost our livelihood. We want to live a normal, peaceful life," an unidentified woman says in the video.

"There are lots of children in here - they're hungry. Get us out of here."

Reuters could not independently verify where or when the video was shot.

(Reporting by Reuters journalists; Writing by Costas Pitas, Lincoln Feast, Robert Birsel; Editing by Himani Sarkar and Philippa Fletcher)