PRISTINA, Serbia (Reuters) -- An explosion in Kosovo destroyed a railway line used primarily by minority Serbs but no one was hurt, UN police in the breakaway Serbian province said on Saturday.

The so-called "Freedom of Movement Train" that thousands of Serbs scattered across Kosovo use to reach northern Mitrovica, where many Serbs live, was halted on the tracks before the site of the explosion, just short of a river crossing.

The blast happened on Friday evening near the northern town of Vucitrn. It destroyed several meters of track and could have caused the train to plunge into the river. "It's a passenger train primarily utilized by Serbs," said UN police spokesman Larry Miller. "But the train never made it to the bridge."

Tensions are running high in the UN-run province since Western powers and Russia opted in November to delay until 2007 a decision on the 90-percent Albanian majority's demand for independence.

The United Nations, which has run the territory since NATO bombs drove out Serb forces in 1999, urged patience on Friday following reports of armed men patrolling roads in the west.

Kosovo's 100,000 remaining Serbs, who want to remain part of Serbia, have been the targets of sporadic violence since 1999.

A NATO bombing campaign that year drove out Serb forces accused of ethnic cleansing and atrocities against Albanians in a two-year war with guerrillas.

UN envoy Martti Ahtisaari is due to present his proposal on Kosovo's "final status" after a general election in Serbia on Jan. 21.