Bosnian Serb police have launched a large-scale search for war crimes fugitive Mr Radovan Karadzic.
A spokesman said police had received information that wartime Bosnian Serb leader Mr Karadzic, wanted by the UN war crimes tribunal in The Hague, was near the town of Bratunac, in a hardline nationalist region bordering Serbia.
"We obtained credible information yesterday that Radovan Karadzic was in the area of Bratunac," said Mr Dragomir Peric, a police spokesman in nearby Bijeljina. "This was the reason to engage a large number of police forces in the search operation."
"The operation has not yielded any results yet and it will last as long as there is justification for it to go on," he said.
It would be one of the first big actions to hunt down Mr Karadzic by Bosnian Serb authorities, often accused by the West of not doing enough to arrest war crimes suspects, which is a key condition for closer ties with the rest of Europe.
A spokesman for the NATO-led SFOR peacekeeping force, which has stepped up its hunt for Mr Karadzic in recent months, said some of its units were supporting police in the action, but he did not confirm they were looking for Mr Karadzic.
"I cannot go into details of this operation," said Captain Dave Sullivan.