BELGRADE, March 18 (RIA Novosti) - UN officials in Kosovo told a joint press-conference on Tuesday the clashes in the self-proclaimed state on Monday, when a Ukrainian peacekeeper was killed and dozens injured, were orchestrated.

The violence in the Serb-dominated area of Mitrovica began when UN police and NATO-led KFOR troops launched an operation Monday morning to regain control of a UN court building seized last week by ethnic Serbs.

Larry Rossin, a senior official with the UN mission in Kosovo, told local media in Pristina on Tuesday that, "It is clear to us that the violence was orchestrated," adding, "we believe we know who was responsible for this."

Serb rioters attacked UN forces with rocks, grenades and Molotov cocktails as they tried to remove protesters from inside the courthouse.

Belgrade has accused the peacekeepers of using excessive force against the demonstrators and sent a letter of complaint to the UN Secretary General, which has been reportedly received.

According to latest reports, over 100 Serbs have been wounded in the worst outbreak of violence in the region since Kosovo declared independence on February 17.