THE HAGUE, The Netherlands -- Kosovo's former prime minister, who resigned last week and surrendered to a U.N. tribunal, has pleaded not guilty to war crimes charges at the U.N. tribunal for the former Yugoslavia. Ramush Haradinaj, 36, has been charged by a United Nations tribunal with 37 counts of war crimes including murder, rape and deportation of Serbs during the 1998-99 war between ethnic Albanians and Serb forces. Haradinaj surrendered to the court a day after resigning as the province's prime minister following an indictment by the war crimes court. Two other alleged Kosovo Albanian rebel commanders also turned themselves in. Haradinaj, a former commander of the Kosovo Liberation Army (KLA), was charged with 17 counts of crimes against humanity and 20 counts of violations of the laws or customs of war. Two of Hardinaj's former KLA aides, Idriz Balaj and Lahi Brahimaj, pleaded not guilty at the same hearing to 16 counts of crimes against humanity, including detention, deportation, murder and rape, and 19 counts of violations of the laws or customs of war. Haradinaj, considered a hero by many Kosovo Albanians, is the most senior former Kosovo guerrilla to be indicted for alleged atrocities. "Haradinaj ... established a system whereby individuals were targeted for abduction, mistreatment and murder, and whereby a systematic attack on vulnerable sections of the civilian population was carried out," the indictment said. "Haradinaj personally ordered, controlled and participated in beatings" of civilians, it added. Haradinaj could face life imprisonment if convicted of any of the charges. He has called evidence against him an attempt to discredit the KLA by those close to former Yugoslav President Slobodan Milosevic. Milosevic has been on trial at the Hague since February 2002, charged with genocide, crimes against humanity and war crimes in Croatia, Bosnia and Kosovo in the 1990s. Haradinaj's selection as prime minister late last year was immediately opposed by the government of Serbia-Montenegro. Fighting raged at the end of the 1990s in Kosovo, an autonomous region in southern Serbia. It has been under U.N. administration since 1999, when NATO forces drove out mainly Serbian Yugoslavs during bloody fighting between the province's majority Albanians and minority Serbs. NATO peacekeepers have been out in force throughout Kosovo since Haradinaj flew to The Hague, with 1,000 more troops being flown in to prevent unrest by Kosovo's ethnic Albanians. International officials praised Haradinaj -- a seasoned battlefield commander with a fiery temper and a loyal following -- for his decision to cooperate with the court and called on other countries in the region to follow his example. Soren Jessen-Petersen, head of the U.N. Mission in Kosovo (UNMIK), said he respected Haradinaj's decision but could not "hide the fact that his departure will leave a big gap." He said Haradinaj's decision to cooperate despite maintaining his innocence is a mark of Kosovo's "growing political maturity."