Serbia has denied reports that it knows the whereabouts of key war crimes fugitive Ratko Mladic.
Gen Mladic, on the run since 1995, has been charged with genocide and other crimes over the Bosnian war.
The interior minister said authorities had information on Gen Mladic, but they did not have enough to locate him.
Correspondents says the comments come amid growing speculation that Belgrade has been negotiating with Gen Mladic on his surrender to the Hague tribunal.
The government has faced international pressure to find and extradite Gen Mladic and former Bosnian Serb leader Radovan Karadzic.
UN war crimes prosecutor Carla del Ponte has urged Serbia to arrest the two by the end of this month.
Interior Minister Dragan Jocic told a parliamentary body in charge of Serbian security there was a "realistic possibility" that war crimes suspects including Gen Mladic were hiding in Serbia.
"But they are experienced warriors, the men who survived the war under difficult circumstances and they know how to do it," he said.
The BBC's Nick Hawton in Sarajevo says local media reports have suggested for some time that Gen Mladic has been in negotiations for his handover to the UN war crimes tribunal.
This weekend, a well-connected former police chief of Belgrade was reported as saying decisive talks were taking place for a surrender, and Gen Mladic was seeking guarantees for his family and supporters.
However, our correspondent says there have been many false dawns regarding the arrest of Gen Mladic and Mr Karadzic - and it is not yet clear whether the latest reports will lead to a breakthrough.