Updated

A United Nations envoy called off talks with the rival leaders of ethnically divided Cyprus on Friday after failing to find "common ground" on convening a final summit to aim for an overall reunification deal.

It is seen as the biggest setback to the negotiations since they began two years ago, but the U.N. said the years-long peace process had not collapsed.

Espen Barth Eide had been meeting separately with the leaders and said that despite serious efforts to overcome differences there is "no prospect" for agreement on the summit's details. He said he would consult with U.N. Secretary-General Antonio Guterres on the next steps.

The peace process hasn't fallen apart, Aleem Siddique, spokesman for the U.N. in Cyprus, told The Associated Press. He said it's now up to the island's Greek Cypriot President Nicos Anastasiades and Turkish Cypriot leader Mustafa Akinci to decide on the way forward.

The island was split in 1974 when Turkey invaded following a coup by supporters of union with Greece.

The negotiations that began in May 2015 have made significant progress on how to share power in an envisioned federation, but they have stumbled on pivotal issues of post-reunification security arrangements and how much territory each side would administer.

The current impasse concerns the 35,000 troops that Turkey keeps in the breakaway Turkish Cypriot north. Greek Cypriots want all Turkish troops gone as part of any deal and propose an international police force to oversee security. The minority Turkish Cypriots say the troops are their only security guarantee. Turkish officials have said there can be no peace deal without a Turkish troop presence.

Anastasiades wants to resolve the security issue at a final summit before settling remaining disagreements. Akinci insists on negotiating all outstanding issues together as part of a give-and-take process.

Akinci on Friday said he wouldn't accept Anastasiades' "preconditions" to a summit.

Anastasiades said he "deeply regretted" Akinci's rejection of his proposal, as well as Eide's invitation for a face-to-face meeting on Monday.