Marathon talks in Switzerland aimed at ending the decades-old conflict in Cyprus wrapped up early today without a deal, UN Secretary General Antonio Guterres said.

The UN-backed talks that began in the Swiss Alpine resort of Crans-Montana on 28 June had been billed as the best chance to end the island's 40-year division.

"I am deeply sorry to inform you that despite the very strong commitment and engagement of all the delegations and the different parties ... the Conference on Cyprus was closed without an agreement being reached," the UN chief told reporters.

Mr Guterres himself was upbeat when he first joined the talks late last week, describing the negotiations as "highly constructive".

He urged the rival Cypriot sides to seize "a historic opportunity to reach a comprehensive settlement to the conflict that has divided Cyprus for too many decades".

But the tone quickly soured and the UN chief flew back to Switzerland early Thursday in a bid to try to end the stalemate that had set in.

He held a full day of back-to-back meetings with President Nicos Anastasiades, the Greek-Cypriot leader, and his Turkish-Cypriot counterpart Mustafa Akinci, as well as the foreign and European affairs ministers from so-called guarantor powers Greece, Turkey and Britain.

But after pushing negotiations into Friday, just hours before he was set to leave for the G20 summit in Hamburg, Mr Guterres was forced to acknowledge that the talks ended "without a result."

"It was obvious that there was still a significant distance between the delegations on a certain number of issues, and a deal was not possible," he said, without providing more details.

He stressed though that while the Crans-Montana conference had proved fruitless, "that doesn’t mean that other initiatives cannot be developed in order to address the Cyprus problem."

Cyprus has been divided since 1974 when Turkish troops invaded and later occupied its northern third in response to an Athens-inspired putsch seeking union with Greece.