"We have reduced the problems to just one," an EU spokesman said, as last-ditch talks continued with local Bosnian Croat and Muslim leaders. In Dublin, the EU's Irish presidency said in a statement: "The securing of agreement remains a matter of extreme urgency."
The EU, which has had a mandate to administer the city of Mostar since July 1994, had originally threatened to abandon its role by midnight last Saturday if the Bosnian Croats refused to join the newly elected city council, where Muslims have a slim majority.
However, when the deadline passed with no agreement in sight, the EU decided to continue the talks rather than walk out and risk making the partition of Mostar permanent.
At one level, the crisis has centred on the refusal of the Bosnian Croats to recognise the validity of the local elections last June, which resulted in a narrow victory for a Muslim-led coalition. At a deeper level, however, the crisis is about the attempt of the Bosnian Croats, supported by neighbouring Croatia, to maintain a Croat political entity in south-west Bosnia that might one day unite with Croatia itself.
Mostar has been divided into a Croat-controlled west and a Muslim-held east since the war between Muslims and Croats of 1993-94. The Croats regard the city as the capital of Herzeg-Bosnia, the separatist mini-state which they promised last week to dismantle in accordance with the Dayton peace agreement.
Carl Bildt, the international mediator from Sweden, said it was vital for the EU not to make any concessions to the Bosnian Croats which might "dilute the election results" in Mostar. Such concessions would severely damage next month's all-Bosnian elections, by opening the way for Serbs, Muslims and Croats alike to reject any results that went against them, he said.
"The main problem was that the Croats refused to recognise the election results because they were not satisfied with the outcome," Mr Bildt's deputy, Michael Steiner, said. He dismissed the Croat claim of irregularities in the vote: "This was a pure pretence. If it had not been this, it would have been something else."
Major Brett Boudreau, a spokesman for the Nato-led peace force in Bosnia, said the crisis in Mostar represented "a major instance of non-compliance on the part of the Bosnian Croats. It is a slap in the face of all those who want democracy in Bosnia."
Bowing to intense pressure from the United States and the EU, the Croats offered last weekend to abide by the election results until the constitutional court of the Bosnia's Muslim-Croat federation ruled on their complaint that the election had been marred by fraud. However, as so often in Bosnian negotiations, this proposal contained a couple of catches.
The main one was that the constitutional court has not yet been formed, and the Croats made their acceptance conditional on there being no city council meetings between next Thursday and an eventual ruling by the court.
If the formation of the court, or its ruling, were to be indefinitely postponed, Mostar would still in practice be without a unified city council.
The Muslim mayor of the eastern part of Mostar, Safet Orucevic, insisted that the Croats should at least accept a deadline for the court's ruling. However, the two sides were unable to bridge this difference, causing the talks to break up early yesterday after seven hours.
The Mostar crisis has coincided with a rise in tensions between Muslims and Croats elsewhere in Bosnia.
Two weeks ago a mosque was set on fire in the predominantly Croat town of Prozor, and an explosion damaged a Catholic church in the Muslim-controlled town of Bugojno, in central Bosnia.Reuse content