Kosovo anti-riot police arrested dozens of ethnic Albanians protesting in front of the UN mission on Wednesday, in the latest tension ahead of talks on the fate of the disputed Serbian province.
Some 100 activists gathered outside the UN headquarters in the capital, Pristina, spraying UN vehicles with graffiti and calling on the UN mission to quit the province.
The United Nations has run Kosovo since 1999, when Nato bombing drove out Serb forces accused of atrocities against civilians as they fought separatist guerrillas. In limbo since, ethnic Albanians who make up 90 percent of the population are impatient for formal independence.
Diplomats say Western powers will steer them towards a form of "conditional independence" in talks due to start in November. But publicly the West is urging compromise with Serb leaders in Belgrade, who say Kosovo should remain within Serbia's borders.
Many of Kosovo's 1.9 million ethnic Albanians see the UN-backed talks as an attempt to delay full independence.
"The UN regime imposed against the will of the people represents a denial of freedom," said a flyer handed out during the protest under the slogan "No Negotiation, Self-Determination".
The group of political activists called the Kosovo Action Network, which has staged small protests before, has sprayed the slogan in towns across Kosovo.
The UN Security Council is expected to endorse the start of so-called final status negotiations at a session on October 24, after which Secretary-General Kofi Annan will appoint a special envoy to mediate between Belgrade and Pristina.
Visiting the Albanian capital, Tirana, on Wednesday, Kosovo's UN governor, Soren Jessen-Petersen, told reporters the envoy would begin his mission in November. "The status quo is no longer tenable," he said.
Analysts say the international community fears a fresh outbreak of violence in the volatile, impoverished province - home to Nato's largest peacekeeping operation - if it delays talks much longer.
Adding to the sense of pressure, UN police on Wednesday vowed to crack down on what it said was an armed group that has emerged in western Kosovo, stopping traffic and searching cars.
A Nato official told Reuters on Tuesday the masked, armed men were criminals and dismissed media reports of a new rebel army.