Cyprus' rival leaders held productive talks over their divided island's future Thursday in their first substantive meeting aimed at ending nearly 35 years of stalemate, a U.N. envoy said Thursday.

Cyprus President Dimitris Christofias and Turkish Cypriot leader Mehmet Ali Talat did not reveal details of their nearly 4 1/2-hour meeting, held in an abandoned airport inside the U.N.-controlled buffer zone splitting the two sides.

But United Nations special envoy Alexander Downer was positive.

"It's been a good discussion today but there's obviously a long way to go," said Downer, a former Australian foreign minister.

"The talks have been productive and the talks have been fruitful," he said.

The two leaders will meet again Sept. 18.

Christofias told reporters later that "now is not the time" to say whether he was pleased with Thursday's talks.

"I cannot predict anything with any certainty," he said.

Talat and Christofias began the latest round of talks on Sept. 3 _ the first negotiations in four years on the Mediterranean island's future. Cyprus was divided in 1974 when Turkey invaded in response to a coup aimed at uniting the island with Greece.

After a largely ceremonial first meeting last week, Thursday's talks began tackling difficult issues that had derailed past efforts.

At the top of that list is the structure of a reunited federal Cyprus and how the Greek Cypriot majority would share power with the minority Turkish Cypriots. Security arrangements and the fate of property lost mainly by Greek Cypriots also remain unresolved.

"These are big issues, discussing something like governance and power-sharing for a constitution is a big question," Downer said. "So inevitably it will take a bit of time."

There is no deadline but Talat has said he hopes to reach an agreement this year.

The U.N. envoy said the two leaders would continue discussions on governance and power-sharing next week. They will move to property issues in subsequent meetings.

Christofias and Talat have promised an unprecedented joint commitment to work toward a solution in that has raised expectations for an end to the decades-long deadlock. They have agreed in principle on a federal structure but remain at odds on the power of central government.

Turkish Cypriots seek a loose federation, fearing dominance by Greek Cypriots who outnumber them by roughly four to one. But Christofias wants a stronger central government to prevent Cyprus from sliding back into partition.

Other contentious issues include whether Turkey will maintain a military presence on the island and whether it will keep intervention rights granted when Cyprus gained independence from Britain in 1960.

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