Bosnian Serb General Ratko Mladic has evaded capture for years
European Union peacekeepers in Bosnia have been searching houses belonging to relatives of the former Bosnian Serb military leader, Ratko Mladic.
He is wanted by the UN to face war crimes charges in connection with the Bosnian conflict of the 1990s.
Local police and Nato troops joined the latest search, raiding homes belonging to the former general's sister and sister-in-law near Sarajevo.
Ratko Mladic has been on the run for nearly a decade.
The BBC correspondent in Belgrade, Helen Fawkes, says a number of items have been taken away for examination.
She says the last time EU peacekeepers mounted an operation like this was six months ago, when they raided the family home of the former Bosnian Serb political leader, Radovan Karadzic.
Mr Karadzic was detained soon afterwards and is now on trial at the UN's war crimes tribunal in The Hague.
The handover of Gen Mladic is a key requirement of the European Union for closer ties with Serbia.
Speculation that he would be seized increased after the arrest of Radovan Karadzic in July last year.
Mr Karadzic was found to have spent years living in the Serbian capital, Belgrade, using a new name and practising alternative medicine.
Correspondents say the capture of Ratko Mladic would be a significant success for The Hague tribunal, which has vowed to stay in operation until he can be brought to trial.
Prosecutors at The Hague believe he directed some of the worst atrocities of the Bosnian war, including the siege of Sarajevo and the massacre at Srebrenica, in which at least 7,500 unarmed Bosnian Muslim men and boys were killed.