VIENNA, Austria - With observers warning of the threat of renewed unrest in Kosovo, the province's prime minister vowed Thursday to declare independence if a final push for a diplomatic settlement between now and Dec. 10 doesn't result in statehood.

The ultimatum by Prime Minister Agim Ceku reflected the growing impatience among Kosovo's ethnic Albanians, who make up 90 percent of the province's 2 million people and are tired of waiting for a formal break from Serbia.

International envoys overseeing a last-ditch round of negotiations said there was no progress Thursday in a closed-door session in Vienna on ending the stalemate with Serbia, which insists on keeping Kosovo within its borders.

Serbia's minister for Kosovo, Slobodan Samardzic, said he offered Kosovo's leadership broad autonomy that would give it "more powers than it ever had in its history."

But Ceku said Albanians would settle for nothing short of full independence -- and would declare it if a Dec. 10 U.N. deadline passes without a negotiated settlement.

"No more delay. We cannot afford further uncertainty. We need a decision," Ceku told The Associated Press.

Ceku said he would press to "open a way for us to declare independence." If that doesn't happen, he said, "we have to declare, and we are going to ask the international community to recognize us."

Although Kosovo remains formally part of Serbia, it has been run by the U.N. and NATO since 1999, when NATO airstrikes ended a Serbian military crackdown on ethnic Albanian separatists in the southern province.

A draft U.N. plan would have given Kosovo internationally supervised statehood. But Serbia bitterly opposed it, and Russia sided with Belgrade, effectively blocking its approval by the U.N. Security Council.

Ceku's warning drew an immediate response in Belgrade, where Serbian Prime Minister Vojislav Kostunica urged the international community not to let Kosovo break away. "The Serbian government will annul any act of unilateral independence," he said Thursday.

The specter of a unilateral declaration of independence also appeared to rattle the so-called "troika" of U.S., Russian and European Union envoys who are supervising the latest talks.

EU representative Wolfgang Ischinger said after meeting separately with the rival delegations that he obtained assurances that "no acts or statements would occur from either side which might jeopardize our troika process and might be regarded as provocative for the future."

Ischinger said the talks would continue in mid-September and at next month's U.N. General Assembly in New York, and that the two sides would meet face to face "as soon as possible."

Serbian Foreign Minister Vuk Jeremic cautioned against any violence as the talks enter what he called "a very delicate stage."

"There has to be an absolute commitment to peace. Violence or threats of violence ... are absolutely unacceptable," Jeremic said.

Ceku did not mention any violence, and tempered his independence remarks by insisting that Kosovo was "equally committed to building working relationships with our neighbors."

"We want to treat Serbia as an equal partner," he told the troika, according to a text of his remarks distributed to reporters.

Both sides said they refused to discuss the idea of carving up Kosovo along ethnic lines, and Ischinger said partition was not on the agenda. Earlier this week, the Netherlands suggested it might be a workable compromise if the rival sides agreed.

But the Contact Group of the U.S., Britain, France, Germany, Italy and Russia, which is brokering the final round of negotiations, has publicly ruled out partition as a dangerous precedent.

With tensions rising on both sides, the turbulent region could see renewed violence if Kosovo does not gain supervised independence, a leading think tank warned earlier this month.

"With Kosovo Albanians increasingly restive and likely soon to declare unilateral independence in the absence of a credible alternative, Europe risks a new bloody and destabilizing conflict," the International Crisis Group said, urging the EU "to avoid chaos on its doorstep."