ATHENS, Greece -- A UN mediator held talks with officials in Athens on Tuesday, amid redoubled efforts to end an unusual dispute that has poisoned relations between Balkan neighbours Greece and Macedonia for a quarter-century.

Matthew Nimetz said it makes no sense to wait much longer to resolve the disagreement on what Macedonia can officially call itself -- an issue befuddling to most outsiders that is a result of the nationalist and historic currents that shaped Balkan history.

"I think there is a momentum here and we should seize the momentum," he told journalists after a meeting with Greek Foreign Minister Nikos Kotzias -- and ahead of similar talks in Macedonia's capital Skopje.

"There's a time for decision-making and I think we're there," Nimetz said. "So I think, in my view, we're talking about weeks of discussion to see where we are."

The dispute broke out after Macedonia, for decades a part of the former Yugoslavia, gained independence in 1991. Greece objects to its use of the name Macedonia, arguing that this implies territorial claims on its own adjoining province, also called Macedonia, that was home to one of the most famous ancient Greeks -- Alexander the Great.

Officials in Skopje counter that their part of the world has been known as Macedonia for a long time.

The squabble has prevented Macedonia from joining NATO, to which Greece already belongs. The left-led governments in both countries have pledged to seek a solution this year.

"I think there is a will (in Athens), and I believe also in Skopje, to try to reach a settlement," Nimetz said.

Greek officials favour a compound name that will somehow qualify the word Macedonia, although it is unpopular with the right-wing populist party that is the junior government partner in Athens.

Many Greeks object to any use of the word Macedonia in their northern neighbour's name. A nationalist rally in the northern city of Thessaloniki drew more than 100,000 people on Jan. 21, and a similar rally is scheduled in Athens on Sunday.