"Despite their difference on substance and on the time frame, I am still convinced that between now and the end of June they can resolve all the core issues provided they go about their task decisively and with the necessary political will," he said.

The Turkish Cypriot President Rauf Denktash had signalled difficulties in the talks after a late meeting on Wednesday night, when he said: "It is impossible to reach an agreement by June. Mr Annan accepts this state of things."

'Despite the doubts'

However, Mr Annan refused to concede that a June deadline would be missed.

"At the end of June we will make an assessment how far we have cracked the core issues... I am not saying a signed and sealed agreement but at least they (will) have resolved the core issues by June," he said.

Remembering relatives who vanished after the Turkish invasion of 1974

"We can make substantial progress by end of June despite the doubts on the part of Mr Denktash."

The Greek Cypriot President Glafcos Clerides simply described his talks with Mr Annan as "very good".

Mr Denktash has been meeting Mr Clerides three times a week for the last five months to try and resolve some of the issues that threaten to derail Cyprus's bid to gain EU membership by 2004.

President Clerides is seeking the reunification of Cyprus as a single state with two distinct zones and a shared central government.

Mr Denktash, by contrast, is still believed to be insisting on recognition for the breakaway state of Northern Cyprus, which is currently recognised only by Turkey.