Yuri Fokine, speaking on BBC TWO's Newsnight programme, said he had written to UK Foreign Secretary Robin Cook calling for the six-nation Contact Group on the former Yugoslavia to meet in Moscow.

But he said the air strikes must stop first.

Mr Fokine attacked the Nato action as contrary to international law.

He said: "We must remember that breaking international law leads to catastrophes.

Threat of 'Third World War'

"We had two already in Europe. Do we want to have a Third World War, or what?"

Professor John Ericsson of the University of Edinburgh: "This is not just empty rhetoric"

The ambassador said Russia might reconsider its adherence to the UN arms embargo if President Slobodan Milosevic's regime continued to come under attack.

Asked if Russia was complying with the embargo, he said: "Well we are, although I think there is reason to think twice about that.

"This war disrupted quite a few agreements regarding Yugoslavia and I am sure there is need to study the matter once again."

'Dangerous precedent'

Mr Fokine said the Nato attacks were setting a dangerous precedent and could encourage nationalist sentiments across Europe.

He suggested the West was playing into the hands of the ethnic Albanian Kosovo Liberation Army (KLA), which wanted to secede from Yugoslavia.

A Lenin look-alike in Moscow carries a placard urging the US to stop its "aggression"

"It's a signal to the nationalistic elements all around Europe that they can have their way and destroy the existing state," he said.

Mr Fokine was speaking as three US B-52 bombers returned to RAF Fairford in Gloucestershire after completing a mission against Serbian targets.

Earlier, in a speech to the House of Commons, Mr Cook said the decision to order Nato strikes came only after tireless efforts to find a diplomatic solution.

'Milosevic to blame'

He said: "We have tried repeatedly - right up the the last minute - to find a way to halt the repression of Kosovo Albanians through negotiation.

"It was not possible, and the person who made it impossible was President Milosevic.

"We were left with no other way of preventing the present humanitarian crisis from becoming a catastrophe, than by taking military action to limit the capacity of Milosevic's army to repress the Kosovo Albanians."