Belgrade's failure to locate the wartime Bosnian Serb commander led the European Union to suspend pre-membership talks with Serbia earlier this year, and EU officials have said negotiations can continue only after Mladic is arrested.
Mladic is wanted by the U.N. war crimes tribunal in The Hague, Netherlands, on genocide charges for allegedly orchestrating the 1995 massacre of 8,000 Muslims from Srebrenica and for a brutal three-year siege of Bosnia's capital Sarajevo during the 1992-95 war.
He is believed to be hiding in Serbia under the protection of hardline nationalists in the army and the police, according to the AP.
Serbia's officials insist the government is doing all it can to locate Mladic, but say authorities have been unable to track him down. They indicated foreign agents have been called in to help.
Serbia's Prime Minister Vojislav Kostunica will summon representatives of the country's security services later this week over their failure to capture Mladic, government officials have said.
Kostunica wants to create and "action plan" to capture Mladic that also includes the participation of foreign agents in the search, the officials told The Associated Press on condition of anonymity because they were not authorized to speak publicly on the issue.
The state television station said the CIA "is already involved" in the search for Mladic. The U.S. embassy in Belgrade has refused to comment.