Ukraine 'Fighting For Very Survival': US Vice President Joe Biden

The United States and Europe must stand together over Ukraine as it battles for survival in the face of escalating Russian military involvement, US Vice President Joe Biden said during a visit to Brussels on today.

"We, the US and Europe as a whole, have to stand with Ukraine at this moment," he said, amid reports of transatlantic divisions over whether to send weapons to support the Western-backed Kiev government.

"Russia cannot be allowed to redraw the map of Europe."

Mr Biden also criticised Russian President Vladimir Putin, who is to meet the leaders of France and Germany in Moscow later today, of riding roughshod over peace efforts.

"Ukraine is fighting for their very survival right now," Mr Biden told reporters alongside EU president Donald Tusk.

"Russia continues to escalate the conflict by sending mercenaries and tanks and, as we euphemistically say in the United states, little green men, without patches, very sophisticated special operations soldiers.

"President Putin continues to call for new peace plans as his troops roll through the Ukrainian countryside, and he absolutely ignores every agreement his country has signed in the past."

Mr Tusk - the former Polish premier who has spoken out strongly in the past against Russia's alleged support for pro-Kremlin separatist forces in Ukraine - said the West must keep up pressure on Russia.

EU officials said Thursday that the bloc will blacklist more Russian individuals over Ukraine, but divisions within the 28-nation bloc, particularly with the new Greek government, have prevented further broad economic sanctions.

"The European Union and the United States need to continue standing shoulder to shoulder, coordinate our efforts and uphold the pressure on Russia for as long as necessary," said Mr Tusk.

In an apparent warning to German Chancellor Angela Merkel and French President Francois Hollande as they visit Moscow, Tusk warned against any deal with Moscow that would break up Ukraine.

"We cannot compromise on Ukraine's independence, sovereignty and territorial integrity," he added.