A year of contentious talks on the future status of Kosovo ended Saturday in a bitter deadlock over a U.N. plan that would set the disputed Serbian province on the road to independence.

Serbia's nationalist prime minister, Vojislav Kostunica, warned of "the most dangerous precedent in the history of the U.N." if the Security Council — which will have the final say — approves the plan.

Kostunica said the blueprint, which would grant Kosovo supervised statehood and elements of independence including its own army, flag, anthem and constitution, could encourage other independence-minded regions around the world to break away. Serbian President Boris Tadic said he found the idea of parting with the province "unbearable."

Kosovo has been a U.N. protectorate since 1999, when NATO airstrikes on Belgrade ended a Serbian crackdown on ethnic Albanian separatists in the southern province. The U.N. plan is an attempt to resolve the final major dispute remaining after Yugoslavia's bloody 1990s breakup.

Kosovo President Fatmir Sejdiu made it clear that his ethnic Albanian majority sees eventual independence as the only acceptable outcome.

"Independence is the alpha and omega — the beginning and end of our position," Sejdiu said, adding that ethnic Albanians "look forward to one day joining the family of free nations."

U.N. special envoy Martti Ahtisaari conceded that last-ditch efforts to get the rival sides to agree on his proposal fell apart after they failed to reach any common ground.

"No amount of additional negotiations will change that," an exasperated Ahtisaari told reporters, adding: "It is my firm conclusion that the potential of negotiations is exhausted."

The former Finnish president said he would now deliver the package to the Security Council by the end of the month.

An agreement was not required for the plan to go up for a Security Council vote, but it would have helped prevent a possible diplomatic showdown there: Although the United States and the European Union support the plan, it has drawn criticism from Russia, an ally of Serbia that wields veto power at the United Nations.

Ultranationalists in Serbia have threatened to stage an uprising if Kosovo is granted independence, but Tadic made clear Saturday that his government "has refrained so far, and will refrain in the future, from the use of force."

Kosovo Prime Minister Agim Ceku played down disappointment among some ethnic Albanians that the plan would not provide full and immediate statehood.

"This proposal for sure will give Kosovo independence," he said, urging a speedy Security Council resolution abolishing Serbia's sovereignty over the province.

Sejdiu, however, acknowledged that Kosovo's leaders made "very painful compromises" by agreeing to give the dwindling Serbian minority broad rights in running their daily affairs.

Serb displeasure ran deeper.

Inside Saturday's closed-door talks at Vienna's ornate former imperial Hofburg Palace, Kostunica said he was outraged that Serbia could end up losing 15 percent of its territory, requiring "new redrawing of borders and endanger the foundation on which international order is based."

Western officials fear that impatience is growing among Kosovo's ethnic Albanians, who have pressed for independence since the early 1990s, and that tensions could plunge the turbulent region back into violence.

Some ethnic Albanians have already staged bloody street protests, saying the plan offers too many concessions to the Serbs and stops short of granting Kosovo full independence. And the Serb-dominated north has vowed to secede if the province gains statehood.