In Moscow, Russian Defence Minister Igor Sergeyev promised to deliver an ``adequate'' response should Washington lead an assault on Yugoslavia that he threatened could spill over into a Vietnam-style conflict.

And, in New York, diplomats said that Russia had signalled it would seek an emergency meeting of the UN Security Council whenever the NATO campaign began.

The situation in Kosovo was not on the agenda, diplomats said. But the Council was ready for an emergency meeting if and when NATO air strikes began, they said.

Primakov meanwhile vowed ``Russia will not sell out its principles'' as it tried to defend Yugoslavian President Slobodan Milosevic against NATO strikes. Milosevic had told Primakov that his country remains ``attached to a peaceful andpolitical solution,'' to the Kosovo crisis, the Yugoslav state agency Tanjug reported.

Russian President Boris meanwhile said he had had a detailed discussion with US President Bill Clinton and France's Jacques Chirac on the crisis.

``I have just spoken to French President Jacques Chirac and Bill Clinton,'' he said in a taped televised address.

``The talk with Clinton was very lengthy. They said the bombing of Kosovo by military forces of NATO will begin in a few hours.''

He went on to urge world leaders to keep Clinton from making the ``terrifying and tragic'' mistake of launching air strikes against Serbia. ``I address the whole world, I address people who have survived war, I address those who experienced bombings, I address their children, I address all politicians. Let us, while there are a few moments left, convince Clinton not to make this terrifying step,'' Yeltsin said in a forceful and emotional speech. The strikes, he said, would lead to ``a war in Europe, if not worse.''

``Of course, weare doing all that we can. But we cannot do everything.''