The European Union has no choice but to halt talks with Serbia today over Belgrade's failure to hand over the genocide suspect Ratko Mladic, according to a senior European official.
Barring dramatic, last-minute developments, the negotiations will be formally put on ice by the European Commission because of Serbia's lack of full co-operation with the UN war crimes tribunal in The Hague.
Suspension of talks on a trade and political pact will be a blow to Belgrade because they are seen as a precursor to negotiations on full EU membership.
One month ago, the EU was persuaded to give Belgrade more time to hand over the former Bosnian Serb military commander, who is accused orchestrating the massacre of more than 7,000 Bosnian Muslims at Srebrenica in 1995. But yesterday, the European Commission made it clear that its patience has been exhausted.
The European commissioner for enlargement, Olli Rehn, said he would consult the UN's chief war crimes prosecutor, Carla Del Ponte, by phone today before making a formal decision to suspend the next round of talks, scheduled for 11 May.
Mr Rehn added that the "facts are clear enough. We don't see Ratko Mladic in The Hague and to our understanding there is no full co-operation with The Hague tribunal. That means that we don't seem to have any other option than calling off the negotiations with Serbia."
Ms Del Ponte seems unlikely to dissuade Mr Rehn from taking a tough course of action. Speaking in Milan, she said: "I would appreciate it if the EU would strongly support the fact that, if Mladic is not delivered, the suspension of negotiations will be done."
Serbia's Deputy Prime Minister, Miroljub Labus, said that "only a miracle in the next 24 hours can save us, and stories that Rehn might change his mind are groundless." But he provided no reasons for believing that the surrender of Mladic was imminent, saying that his arrest "can be done in a day, but also in five years".
Serbia had hoped to conclude the trade deal, known as a stabilisation and association agreement, before the end of the year. But Mladic's fate has been a persistent obstacle for Belgrade.
European officials are convinced that the Serbian authorities could arrest Mladic, who is widely assumed to be living in the country, if there was sufficient political will to do so.
Belgrade risks a nationalist backlash if it hands Mladic over to a UN court, which is seen domestically as anti-Serb. That problem was exacerbated by the death of the former Yugoslav president, Slobodan Milosevic, while in custody in The Hague.
EU officials said that last month's decision to continue talking to Belgrade followed a promise from the Serbian Prime Minister, Vojislav Kostunica, to push ahead with the arrest by the end of April. At that point, with signs of more pressure on Mladic's support network, Ms Del Ponte accepted the deadline.
Diplomats say that the EU now risks looking weak if it continues with the negotiations.
Last October, Ms Del Ponte ruled that Croatia was co-operating with the UN tribunal despite the fact that its war crimes suspect, Ante Gotovina, was still at large. That allowed formal EU membership negotiations with Croatia to go ahead.
But officials say that, by then, the war crimes prosecutor had been shown evidence that Gotovina was outside Croatian territory. Within weeks he was arrested in the Canary Islands.
In Brussels, officials said talks with Serbia could be resumed as soon as Mladic was in The Hague, or when Belgrade convinces Ms Del Ponte it is co-operating fully.