UNITED NATIONS, March 2 (AFP) - The UN General Assembly on Wednesday (Mar 2) overwhelmingly adopted a resolution that "demands" Russia "immediately" withdraw from Ukraine, in a powerful rebuke of Moscow's invasion by a vast majority of the world's nations.

After more than two days of extraordinary debate, which saw the Ukrainian ambassador accuse Russia of genocide, 141 out of 193 United Nations member states voted for the non-binding resolution.

China was among the 35 countries which abstained, while just five - Eritrea, North Korea, Syria, Belarus and of course Russia - voted against it.

The resolution "deplores" the invasion of Ukraine "in the strongest terms" and condemns President Vladimir Putin's decision to put his nuclear forces on alert.

The vote had been touted by diplomats as a bellwether of democracy in a world where autocracy is on the rise, and came as Putin's forces bear down on Kyiv while terrified Ukrainians flee.

"They have come to deprive Ukraine of the very right to exist," Ukraine's ambassador Sergiy Kyslytsya told the Assembly ahead of the vote.

"It's already clear that the goal of Russia is not an occupation only. It is genocide."

Putin launched the full-scale invasion of Ukraine on Feb 24. Moscow has pleaded "self-defence" under Article 51 of the UN Charter.

But that has been roundly rejected by Western countries who accuse Moscow of violating Article 2 of the Charter, requiring UN members to refrain from the threat or use of force to resolve a crisis.

The European Union's ambassador to the UN Olof Skoog said the vote was "not just about Ukraine".

"It is about defending an international order based on rules we all have signed up to," he said in a statement.

UN Secretary-General Antonio Guterres said the General Assembly's message was "loud and clear".

"End hostilities in Ukraine - now. Silence the guns - now," he said in a statement.

"As bad as the situation is for the people in Ukraine right now, it threatens to get much, much worse. The ticking clock is a time bomb."