High-level talks aiming at reunifying Cyprus have failed to reach an agreement, U.N. Secretary-General Antonio Guterres declared Friday, again dashing hopes that the island's 43-year ethnic split could be healed.

Guterres made the announcement after marathon, U.N.-sponsored talks concluded at a Swiss resort in the early hours of Friday.

"Unfortunately...an agreement was not possible and the conference was closed without the possibility to bring a solution to this dramatically long-lasting problem," Guterres told reporters.

"I want to express my deep gratitude and appreciation to the leaders of the two communities and to wish the best to all Cypriots north and south."

But Guterres didn't entirely shut the door on any renewed, U.N.-assisted attempt to get the island's Greek Cypriot President Nicos Anastasiades and the leader of the breakaway Turkish Cypriots Mustafa Akinci back to the negotiating table again.

"The conference is closed," said Guterres. "That doesn't mean that other initiatives cannot be developed to address the Cyprus problem."

Echoing Guterres, Cyprus government spokesman Nicos Christodoulides said the failed result wasn't "the end of the road" for peace efforts.

"The existing, unacceptable situation can't be Cyprus' future and the president will redouble his efforts," Christodoulides said.

Also participating in the talks were Cyprus' three 'guarantors' — Greece, Turkey and former colonial ruler Britain.

Turkish Foreign Minister Mevlut Cavusoglu said the talks' collapse was owed to a Greek and Greek Cypriot insistence for Ankara to pulls out all of its troops from the island and for military intervention rights to be abolished.

"For Turkey and the Turkish Cypriot side it is not acceptable for troops to be withdrawn," he told reporters.

Security arrangements for an envisioned federal Cyprus were the linchpin to a reunification deal.

The issue revolves around the more than 35,000 troops that Turkey has kept in the island's breakaway Turkish Cypriot north since 1974, when it invaded following a coup mounted by supporters of uniting Cyprus with Greece.

Greek Cypriots in the island's internationally recognized south perceive the Turkish soldiers as a threat and want them to leave. The island's minority Turkish Cypriots want them to stay as their protectors.

Christodoulides faulted Turkey's "obsession" with having a troop presence in Cyprus and the right to militarily intervene. He said Turkish positions on other key issues deviated from a U.N. framework and "were such that they could not be accepted under any circumstances."

Greek Foreign Minister Nikos Kotzias posted on his personal Twitter account that it wasn't possible to accept Turkey's right to militarily intervene on the whole of Cyprus.

"The dream and the plan for solving the Cyprus problem remain alive," said Kotzias.

Other key disagreements were on how much territory would make up the Greek Cypriot and Turkish Cypriot federal zones.

Greek Cypriots sought for the town of Morphou to be returned to Greek Cypriot administrative control so a large number of displaced people could swiftly reclaim lost homes and property. Turkey and the Turkish Cypriots offered only part of the town.

Another key difference was Turkey's insistence that a peace accord grant Turkish nationals the right to relocate and transfer money, services and goods to a reunified Cyprus. Greek Cypriots were reluctant to cede unregulated access to Turkish nationals over concerns that the small island of 1.1 million people would be overwhelmed economically and demographically.