President Slobodan Milosevic is expected to respond today to a joint EU-Russian peace plan for Kosovo, described last night as "the first realistic chance for peace".
The plan, which would involve a ceasefire and Yugoslav withdrawal from Kosovo, and the introduction of both NATO and Russian peacekeeping troops operating under a UN mandate, was put to him last night by the European Union envoy, President Martti Ahtisaari of Finland, and Russia's Balkans envoy, Mr Viktor Chernomyrdin.
Speaking on their arrival at Surcin airport in Belgrade, Mr Ahtisaari said: "This is a historic day for Yugoslavia. Mr Chernomyrdin and I are coming with a peace plan, an offer for peace."
According to an aide to Mr Chernomyrdin, President Ahtisaari presented Mr Milosevic with the plan, worked out earlier in Bonn between Mr Chernomyrdin, Mr Ahtisaari and the US Deputy Secretary of State, Mr Strobe Talbott.
It was discussed in detail, but the Yugoslav leader did not give his response. Talks are to resume this morning.
It remained unclear last night how a peacekeeping force would be commanded, but Mr Chernomyrdin suggested that NATO and Russian contingents would remain separate. NATO would command the NATO force, Russia the Russian forces, he said. But NATO's spokesman, Dr Jamie Shea, was adamant that any peacekeeping force must be under a single command and that there should be no de facto partition of Kosovo.
"As far as NATO is concerned, we are talking about a single force with unity of command, robust rules of engagement and a common approach throughout Kosovo. We are not going to do anything which would encourage future partition, whether real or unreal," he said.
Dr Shea conceded that NATO and Russian forces would occupy separate geographical areas of Kosovo, but insisted that there would be no formal sectors in the province. Western officials fear that, if the Russians are perceived to be too sympathetic to the Serbs, many ethnic Albanian refugees could refuse to return to parts of Kosovo occupied by non-NATO forces.
Any suggestion of partition would also alarm Kosovan leaders. One, Mr Hashim Thaci, a putative leader of any restored Kosovan government, said last night: "We reject categorically any idea of separate zones of international forces . . . We cannot accept the localisation of any non-NATO troops in any part of Kosovo."
However, in a significant concession, Russia agreed that NATO could choose which of its member-states should provide troops for the peacekeeping force.
Britain and the United States are hoping that the force will be commanded by Britain's Gen Michael Jackson, who is leading the massive force already mobilised on Kosovo's borders. Last night President Clinton said he would contribute 7,000 ground troops to any agreed peacekeeping force.
Under the terms of the deal, Kosovo would remain part of Yugoslavia, the Kosovo Liberation Army would be disbanded and a referendum on independence would be ruled out. To save NATO leaders the embarrassment of signing a deal with Mr Milosevic, now an indicted war criminal, the agreement would be imposed by the United Nations Security Council.
After further talks today, Mr Ahtisaari is scheduled to fly to Cologne to brief EU heads of government at their summit. Both he and Mr Chernomyrdin were stressing last night that, despite optimism, talks and further visits to Belgrade were to be expected before any deal was concluded.