The United States Balkan envoy, Mr Richard Holbrooke, was confronting the Yugoslav President, Mr Slobodan Milosevic, yesterday with details of "a grim briefing" he was given on refugee conditions in Kosovo.
Backed by threats of NATO air strikes, Mr Holbrooke headed into a second round of negotiations intended to persuade the Yugoslav president to comply with UN demands to restore peace in Kosovo and settle its political future.
Rebuffed during talks on Monday, Mr Holbrooke told reporters in Pristina: "If (Milosevic) thinks NATO is bluffing, if he wants to take that risk, all I can do is convey to him the views of our government . . . of the seriousness of the situation."
Mr Milosevic is under notice from the US and its European allies in NATO that he faces air strikes within days unless he ends the seven-month conflict in Kosovo with its ethnic Albanian majority who want independence.
Mr Holbrooke met the Kosovo Albanian leader Mr Ibrahim Rugova in Pristina but neither side would comment on the outcome. He told the Albanians, who have boycotted Serb offers to negotiate: "We know how difficult this is, we are doing everything we can to help. We want to help but you have to understand very clearly what we are talking about. This is a very dangerous moment and we have to speak frankly and candidly to each other."
Although Mr Milosevic is the chief target of western anger, the US envoy is also under pressure to force the Albanians to drop their boycott of negotiations. The ethnic Albanian political analyst Mr Veton Surroi, who also met the envoy, said: "It will be an increasingly difficult process . . . and I see a lot of shuttling in these days."
Mr Holbrooke also spoke to monitors of the Kosovo Diplomatic Observer Mission (KDOM) who have witnessed a Serb offensive which has razed scores of villages and driven thousands of ethnic Albanians from their homes in recent weeks.
"It was a very grim briefing . . . there are still huge numbers of refugees up in the hills," he said. "People have come back to their houses but the houses are wrecked, without walls or roofs . . . there isn't much here that we've seen today that is very encouraging."
KDOM monitors told him that Serbian police units involved in the offensive, who were not part of a withdrawal that Mr Milosevic ordered last week, were making their quarters secure for winter. "They are getting ready for winter, which suggests they are going to stay for a very long time and make (refugee) returns even more difficult," Mr Holbrooke said.
Between 800 and 1,500 people are estimated to have died in fighting since March between Serb security forces and separatist guerrillas of the Kosovo Liberation Army (KLA).
The Yugoslav president has insisted there has been no fighting in Kosovo for more than a week and that western humanitarian organisations have hugely over-estimated the numbers of refugees living in the open.
Russia yesterday maintained its diplomatic campaign to prevent the NATO action and was joined by China in a demand for a political solution rather than military intervention. Russia's Interfax news agency said the Moscow government would use its veto in the UN Security Council to stop air strikes. Moscow believes NATO needs UN further agreement to provide a legal basis for any military action.
In a weakening of NATO's own unity of purpose, Germany's Green Party, a likely coalition partner of Chancellor-elect Gerhard Schroder, also cautioned against acting without UN approval.
The United States on Monday said there were signs that Serb forces were pulling back in Kosovo, but added that Mr Milosevic had not done enough to avert air strikes.
President Bill Clinton told President Boris Yeltsin of Russia in a telephone conservation he feared that Mr Milosevic, who enjoys Russian protection, was "playing the classic game of making false promises designed to remove international pressure".
Western diplomats and their dependents in Belgrade were reported to be preparing to leave Yugoslavia in the event of NATO air strikes becoming a certainty, but most embassies were reluctant to discuss their precise plans.
In Moscow the Foreign Minister, Mr Igor Ivanov, said that Russia would veto any move at the United Nations to authorise air strikes against Yugoslavia, raising the stakes in its battle with NATO over the Kosovo crisis.
The Russian news agency Interfax said Mr Yeltsin had told the French President, Mr Jacques Chirac that military actions would not solve the crisis.