President Slobodan Milosevic of Yugoslavia has rebuffed efforts by the US mediator, Mr Richard Holbrooke, to bring a swift end to Belgrade's worsening confrontation with the West over Kosovo.
Tanjug news agency said Mr Milosevic told Mr Holbrooke during talks yesterday that threatened NATO air strikes would be a "criminal act" in support of "ethnic Albanian criminals".
His defiance screwed East-West tensions a notch higher after a day of drama as the West intensified plans to intervene in the conflict between Serbs and the ethnic Albanian separatist majority in the southern Serbian province.
Mr Holbrooke and co-mediator Mr Christopher Hill looked downcast when they returned to their hotel and refused to discuss the substance of their discussions with Mr Milosevic.
But Mr Holbrooke told reporters at NATO headquarters in Brussels which he visited on his way to Belgrade that planning for air strikes was "going forward on a serious, intense and sustained basis as we talk".
The United States has warned Yugoslavia that NATO will attack within days unless Mr Milosevic ends the conflict, withdraws his police and troops from Kosovo and negotiates an autonomy pact for the ethnic Albanians.
Mr Holbrooke said he and Mr Hill, who has been working on a draft peace plan acceptable to both sides, would travel to Pristina tomorrow before returning to Belgrade to tackle Mr Milosevic again.
According to Tanjug, the Yugoslav leader told the Americans there had been "no fighting in Kosovo for a whole week" and that Yugoslavia was providing humanitarian assistance as well as being ready for political talks with the Albanians.
Mr Holbrooke went into the meeting with a stark warning that air strikes were inevitable if Belgrade refused to back down.
A US source said his message was that "there was not the slightest doubt in anyone's mind (in the West) that there would be military action if he did not comply with (last month's) UN resolution".
NATO informants said Mr Holbrooke's mission was to set Mr Milosevic "irreversible, verifiable steps by certain short-term deadlines" towards resolving the conflict.
Although Western governments have mustered a powerful show of determination to assert NATO's credibility, Mr Milosevic appeared to be gambling that doubts about the legality of the action and Russian opposition could help him escape.
Moscow warned NATO governments that air strikes without the approval of the UN Security Council, where Russia wields a veto, could throw East-West relations into a new Cold War.
The West is also facing difficulties in forcing talks on the ethnic Albanian leaders, who insist they will settle for nothing less than independence. The US said before Mr Holbrooke's first meeting with Mr Milosevic that there were signs Serb forces were leaving Kosovo.
But it ruled that Belgrade had still not done enough to avert air strikes on which NATO could take a final decision "in a matter of hours or days".