Several hundred ethnic Serb protesters have stormed a United Nations courthouse in the divided northern Kosovo city of Mitrovica.

U.N. police who were guarding the building retreated as the protesters broke through entrance gates Friday, pushing aside the guards.

The U.N. administrator of Kosovo, Joachim Ruecker, said the protesters had crossed what he called one of his mission's "red lines," and he ordered U.N. police to re-take the building.

The protest coincides with a visit to Kosovo by NATO Secretary-General Jaap de Hoop Scheffer, who is expected to meet with Kosovo's prime minister and president Friday.

Serbia considers Kosovo to be its historic heartland and has rejected Kosovo's declaration of independence as illegal.

The protesters had been outside the building every day since Kosovo's ethnic Albanian majority declared independence from Serbia last month.

Rioters opposed to Kosovo's declaration of independence attacked the U.S. and other embassies in Belgrade last month.

Police detained about 200 people in connection with the violence that left one person dead and at least 130 injured.


Some information for this report was provided by AP and Reuters.