(dpa) - The UN Mission in Kosovo (UNMIK) chief, Joachim Ruecker, on Friday ordered police to "restore law and order" after hundreds of Serb protesters stormed a court building in the hotspot town Mitrovica as the head of NATO visited the former Serbian province.
Some 300 protesters broke through an international police cordon in the northern, Serb-dominated section of the divided Mitrovica and broke into the UN municipal court building, Kosovo police said.
"Those who turned to violence crossed one of UNMIK's red lines. This is completely unacceptable. I have instructed UNMIK Police to restore law and order," Ruecker said after meeting Prime Minister Hashim Thaci and President Fatmir Sejdiu.
Thaci and Sejdiu had called on the UN, which has governed Kosovo since NATO drove Serbian security forces out in 1999, to assert its authority in Mitrovica, where Serbs have been protesting daily since Pristina declared independence from Serbia a month ago.
EU President Slovenia also condemned the attack on the court in Mitrovica. The EU has sent a law-enforcing mission of nearly 2,000 experts to Kosovo to help it along its first independent steps.
"We strongly condemn the attack on UNMIK personnel and the seizure of the court in north Mitrovica," Ljubljana's Ambassador Vojko Volk said in a statement.
Serbs are a majority in northern Mitrovica and make up about a fifth of the population north of the town, while Albanians make up the overwhelming majority in the rest of Kosovo.
Raised tensions persist in northern Kosovo where Serbia has established parallel structures of authority. Belgrade has nodded approvingly even at the violent protests of last month.
Nobody was injured in Friday's incident, but after forcing the police to retreat, the crowd remained in the building, took down the UN flag and put up a Serbian flag, police spokesman Besim Hoti said.
The standoff continued into the afternoon. Serbian media reported that only Kosovo Serbs working in the judiciary remained in the court building, but that a crowd gathered outside to support them.
Meanwhile NATO Secretary General Jaap de Hoop Scheffer arrived on his first visit to Kosovo since the February 17 declaration of independence.
"We received assurances for the continued presence of NATO and its readiness to maintain stability and security in Kosovo," Sejdiu said after meeting De Hoop Scheffer.
NATO, which maintains some 17,000 troops in Kosovo, as well as the international UN police and Kosovo police, have kept a low profile amid protests and riots over the past month.