At least five people were killed Wednesday and dozens were wounded in clashes between Serbs and ethnic-Albanians in Kosovo. The riots in Kosovo's divided city of Kosovska Mitrovica were described as one of the worst outbreaks of ethnic fighting since the war in Kosovo ended in 1999.

Fighting continued in the city hours after United Nations police moved in firing tear gas and rubber bullets to try to disperse protesters.

Eyewitnesses said Serbs and ethnic-Albanians, who are separated by the city's Ibar River, fired at each other across the water, using weapons that included a Kalashnikov rifle and revolvers.

Local people say tensions flared in the troubled town, after two ethnic-Albanian boys drowned in the river. Albanians say the boys were chased into the water by local Serbs in an apparent revenge attack.

Kosovo Albanian television has quoted a boy as saying that he and his friends were chased by Serb children with a dog and jumped into the river to escape. He said he swam with his little brother on his back but the boy slipped off and went under.

Serbs in Kosovska Mitrovica have been angry about a drive-by shooting in a nearby area in which a Serbian teenager was seriously injured.

In an effort to end the fighting, hundreds of Polish anti-riot police formed a cordon Wednesday at a bridge leading to the Serb-populated northern part of the city, firing rubber bullets to disperse the protesters. Hundreds more were also seen on the Serb side of the town.

The latest riots in Kosovska Mitrovica underscored concern that almost five years after the Serbian province was placed under NATO protection and U.N. administration there is no hint of reconciliation.

Leaders of Kosovo's ethnic Albanian majority want independence following a decade of oppression and violence under Serbia's ousted leader Slobodan Milosevic. Belgrade has made clear it wants to keep the province under its control.

U.N.-sponsored talks have failed to break the deadlock.

But Serbia's new Prime Minister Vojislav Kostunica has made a move toward satisfying ethnic-Albanian demands. He says Serbs accused of war crimes will be tried by a special tribunal.

In a first sign of that, a Serbian police officer charged with executing 14 ethnic Albanian civilians and wounding five others during the war, was sentenced to 20 years in prison Wednesday, by the tribunal.

The officer, Sasa Cvjetan, a member of Serbia's notorious "Scorpions" special police, denied the charges.