European Union foreign ministers have failed to end the stalemate over Turkey's bid to join the bloc.
Turkey is threatening to walk away from the talks
Late-night talks in Luxembourg ended without agreement on a negotiating framework to open talks with Turkey, which were due to begin on Monday.
Austria wants the EU to consider giving Turkey "favoured nation" status, but holding off from full membership.
UK Foreign Secretary Jack Straw said failure to agree could harm relations between Christian and Muslim nations.
Turkey's Prime Minister Recep Tayyip Erdogan has said his country will refuse to begin negotiations if it is to be offered anything other than full membership.
The foreign ministers have said they will resume their attempts to end the stalemate on Monday.
Parallel discussions over Croatia's application for full membership of the EU have been delayed as officials redouble their efforts to reach agreement on Turkey.
All 25 member states have to approve a negotiating mandate before talks with Turkey can begin.
"It's a frustrating situation, but I hope and pray that we may be able to reach an agreement," Mr Straw told reporters.
BBC Europe editor Mark Mardell, in Luxembourg, says Mr Straw is determined that the wording of the mandate will not lead to Turkey walking away from the talks.
Mr Straw has argued that keeping Turkey out of the EU would widen the "theological-political divide" between Christian and Muslim nations.
Demands on Turkey
Austria raised last-minute objections to opening entry talks with Turkey, suggesting that the EU should consider the option of a "privileged partnership" status as well as full membership.
Currently the draft negotiating framework says only that full membership is the ultimate aim of any talks.
Chancellor Wolfgang Schuessel has said he wants the EU to acknowledge popular concerns over its expansion.
Turkey needs to make huge efforts to meet the stringent requirements for EU membership, including absorbing the 80,000-page EU rule book into its domestic law.
French Foreign Minister Philippe Douste-Blazy suggested it was "a lot" to ask of Turkey.
EU members agreed in December last year to open accession talks with Turkey in October 2005.
If started, the Turkish negotiations are expected to take about 10 years.
Link to Croatia
Disagreements over Turkey have forced the EU foreign ministers delay a decision on whether to give the green light to membership talks with Croatia.
The issue was put on hold last March because of Zagreb's failure to locate Ante Gotovina, the fugitive general wanted by the UN War Crimes Tribunal.
Officially there is no link between Croatia, a small, prosperous, mainly Catholic country and Turkey, huge, poor and predominantly Muslim.
But correspondents say Austria's chancellor argues that if the EU trusts Turkey to make progress, it must trust Croatia too.