Belgrade (dpa) - An international court in Kosovo on Thursday sentenced a Serb leader to nine years in prison for war crimes committed against ethnic Albanians in a ruling that is set to increase tensions between Kosovo and Serbia.Oliver Ivanovic, regarded as a moderate among Kosovo Serb politicians, was found guilty of the murder and torture of ethnic Albanians in the town Mitrovica during the 1999 war in Kosovo, which was then still Serbia‘s province.The court said that Ivanovic, uniformed as a paramilitary and armed, allowed paramilitaries to take a group of Albanians from army custody and execute them. Four people were murdered.Ivanovic "was aware of the operation of expelling and killing Albanians," the European Union‘s law-enforcing mission in Kosovo, EULEX, said. "He willingly complied with the plan, knowing that it would result in the killings."The head of Belgrade‘s Kosovo office, Marko Djuric, condemned the verdict as a political move to "humiliate Serbia."Djuric told Serbian state TV RTS that Belgrade needs to "find a measured response," but cast doubt on the continuation of normalization talks with Kosovo that the EU is mediating. "This is a red line where we wonder whether to continue and how," he said.The talks are due to resume in Brussels on January 27.The Albanians, who are in a 90-per-cent majority in Kosovo, launched an insurgency against Belgrade‘s heavy-handed rule in 1998.Fighting flared into an all-out war the following year, with NATO intervening against Serbia and eventually ousting its armed forces from the territory. Kosovo declared independence in 2008.Though western powers and nearly all of its neighbours have recognized Kosovo, Serbia continues to claim sovereignty over it and, with the help of its superpower ally Russia, has blocked its promotion to the United Nations.Belgrade and Pristina did, however, agree to normalize relations in return for closer ties with the EU, which both strive to join.