A planned face-to-face meeting between Kosovo and Serbia's presidents in Brussels fell apart at the last minute on Friday, quashing expectations that the former war foes might move closer to a deal to normalise relations.
Kosovo president Hashim Thaci and his Serbian counterpart Aleksandar Vucic each met the EU's diplomatic chief Federica Mogherini separately as part of negotiations led by the bloc to resolve a festering dispute over Kosovo's independence.
A three-way meeting that had been expected did not take place, though Thaci played down reports of a snub by Vucic, saying instead that they were simply too far apart on key issues for the encounter to go ahead.
Serbia refuses to recognise Kosovo, an Albanian-majority former southern province that broke away from the then Yugoslav republic in a bloody war in 1998-1999 and declared independence a decade later.
"It's not the first time we don't have a trilateral meeting," Thaci told reporters in Brussels.
"There was no refusal in terms of not meeting, there was just continuation of the normal work that we have up to now and the differences on the substance were big enough not to allow a trilateral meeting."
The talks have been stalled for months but started generating attention -- and concern -- in recent months after Thaci and Vucic signalled an openness to the idea of border changes.
- 'Differences are becoming bigger' -
The presidents have not laid out any detailed plans, but the talk has alarmed critics, who say redrawing the map of the Balkans could wreak havoc in a fragile region scarred by war.
Thaci had been open about the fact that he wanted to discuss the possibility of bringing the Albanian-majority strip of Serbia, the Presevo Valley, into Kosovo.
The speculation is that it could be traded for Kosovo's Serb-dominated north, which has never submitted to Pristina's authority.
"What becomes clear now is that as we move forward in the discussion, the differences between the two are becoming bigger and although today we discussed only through high representative Mogherini, this has become clear," Thaci said.
Earlier, the Kosovo leader wrote on Facebook that while the "journey will be difficult", it was "indispensable for securing long-term peace in the Western Balkans."
"Kosovo is committed to reaching a final agreement with Serbia, which guarantees mutual recognition, EU, NATO and UN membership," he wrote.
Serbia needs a deal to move forward in EU accession talks, while Kosovo is hoping for recognition from Belgrade that would unlock its path into the United Nations.
Kosovo is recognised by more than 110 countries, but outliers include Russia, China and five EU countries, including Spain, which would not want to set a precedent for its own regions.
Mogherini acknowledged that "difficulties remain" but said she trusted the two presidents' commitment to continue talks and reach a proper agreement in the coming months.