A former Kosovo prime minister has been detained by Slovenian authorities on a 2006 international arrest warrant issued by Serbia.

Ramush Haradinaj, who is now a lawmaker and was on his way back from an official visit to Germany, isn't being allowed to board a flight to his native Kosovo, his party, the Alliance for the Future of Kosovo, said in a statement on Wednesday.

The former guerrilla fighter was cleared of war crimes charges in two lengthy trials by a U.N. war crimes tribunal. But Serbia accuses Haradinaj, who was a senior rebel commander in western Kosovo, of committing war crimes against Serb civilians during the 1998-99 war, including kidnappings, torture and killings.

Haradinaj is now an opposition leader and member of Kosovo's 120-seat multiethnic assembly.