Russia hailed the breakthrough in talks over Kosovo yesterday, but threatened to provide military aid to Yugoslavia if NATO attacks it.
A Russian foreign ministry spokesman, Mr Vladimir Rakh manin, said Moscow welcomed the development and would likely take part in the international monitoring team once it is organised.
But he also warned that any unilateral use of force by NATO would force Moscow to change its policy towards the alliance.
The defence ministry issued a statement saying it might supply direct military aid to Belgrade if NATO launches strikes.
"The defence ministry is studying a complex of possible measures to defend the national interests of Russia and offer aid to the Serb people if NATO begins bombardment of Yugoslavia," the statement said.
"First of all, these measures call for a change in the partnership relations with NATO. Russia will provide military and military-technical support to Yugoslavia," it said.
But a Kremlin spokesman, Mr Dmitry Yakushkin, said only the President, Mr Boris Yeltsin, and the foreign ministry could give official policy and urged the press to "pay no attention to statements by other individuals, including the military".
Mr Rakhmanin said: "If NATO will decide the fate of a conflict through one-sided actions, then definitely this will affect our relationship toward NATO." But he would not comment on what concrete steps Russia might take.
Meanwhile in Minsk, the Bela russian President, Mr Alexander Lukashenko, denounced Romania and Bulgaria for allowing NATO forces to use their airspace in the crisis. Mr Lukashenko expressed shock at moves against Yugoslavia, to which he has offered assistance in case of attack.
Romania and Bulgaria, he said, were "in effect taking part in crimes being prepared in the Balkans" and violating the principle of Slav unity. "The leaders of these former socialist countries are placing their own people under the threat of attack," he said.
"How low do such leaders have to stoop, humiliating their own people? Just to get into NATO, or to be refused entry by the European Union? We are talking about our sacred Slav unity. It has been betrayed and crushed."
In Antalya, the Albanian Foreign Minister, Mr Pascal Milo, said the deal fell short of his hopes for Kosovo. "It is difficult to say that I am fully satisfied with what Holbrooke and Milosevic achieved," he said.