Serbian police raided several locations Monday in search of the alleged war criminal Ratko Mladic, Belgrade media reported quoting sources, reported dpa.
Raids involving special police forces were reported from several locations in and around Valjevo, a town 70 kilometres south-west of Serbia.
The capture of Mladic and his extradition to the United Nations war crimes tribunal is the key remaining condition for Serbia's further progress toward European Union membership.
The Hague-based tribunal accused Mladic of genocide and other crimes against humanity for his role as the commander of the Bosnian Serb army during the 1992-95 Bosnian war.
He is held responsible for atrocities such as the massacre of 8,000 Muslims at Srebrenica and the shelling and sniping of the Bosnian capital Sarajevo.
Mladic is known to have been protected by the Serbian military leadership in Belgrade until at least 2002.
The Bosnian wartime political chief, Radovan Karadzic, was surprisingly caught in Belgrade in July and delivered to The Hague tribunal days later. He is now faces a genocide trial there.