Russia gave Ukrainian fighters holding out in Mariupol a new ultimatum to surrender on Wednesday 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 advancing in what Ukrainian officials have called the Battle of the Donbas.

Russia's nearly eight-weeklong invasion has failed to capture any of Ukraine's largest cities, forcing Moscow to refocus in and around separatist regions in the east.