Ahtisaari said "there was no will" on the part of Serbian and Kosovo ethnic-Albanian leaders to agree on a solution.
Serbian President Boris Tadic and Prime Minister Vojislav Kostunica, and their ethnic-Albanian counterparts in Kosovo, Fatmir Sejdiu and Agim Ceku, met for a final round of talks in Vienna today.
But Ahtisaari said after the meeting that the two sides' respective statements on Kosovo's status "do not include any common ground."
Ahtisaari said he would deliver his proposal for the future of the disputed province to the UN Security Council by the end of the month.
The plan proposes that Kosovo be granted limited, internationally supervised statehood, with its own constitution, army, national anthem, and flag. In exchange, it would give the Serbian minority broad rights in running their daily affairs and preserving their culture.
Kostunica Warns Against 'Snatching' Kosovo
The plan is widely seen as putting Kosovo on the path to independence.
Ethnic Albanians have endorsed it, but Belgrade strongly rejects it.
Serbia's Prime Minister Vojislav Kostunica today said that "snatching Kosovo from Serbia would represent the most dangerous precedent in the history of the UN."
Kosovo has been under UN administration since the end of the 1998-99 war between ethnic Albanian separatists and Serbian forces.
Ethnic Albanians make up 90 percent of the province's two million people, and there are concerns that tensions could plunge the territory back into violence.
(AP, Reuters, AFP)