Kosovo and Serbia failed to agree on a plan after 14 hours of talks between the respective prime ministers, making talks on Serbia joining the EU in June unlikely.
The EU's Catherine Ashton said that the differences of both sides were "narrow and very shallow", and added:
"We have some hours left. I hope in that time, that both delegations will reflect on whether they can take the final steps necessary to finish this agreement and to move their people forward into the future,"
The Serbian prime minister, Ivica Dacic said:
"It is clear however that Pristina (the Kosovo capital) is not ready to go to the very end and that it is obstructing these talks ... and even threatens to resolve the issue of northern Kosovo with some other methods,"
Kosovo's prime minister meanwhile said that Serbia had rejected proposals by Ashton on normalising relations.