War crimes prosecutor Carla del Ponte is due to hold fresh talks in Belgrade, where the government is under pressure to hand over a top war crimes suspect.
Fugitive Bosnian Serb General Ratko Mladic is "holding the whole nation hostage," Serbia and Montenegro Foreign Minister Vuk Draskovic warned.
Gen Mladic, on the run since 1995, has been charged with genocide and other crimes over the Bosnian war.He commanded forces responsible for "ethnic cleansing".
UN tribunal officials in The Hague say Serb hardliners are protecting him.
In an interview with the Associated Press, Mr Draskovic said the failure to catch Gen Mladic was jeopardising Serbia's bid for closer ties with the European Union and Nato and its position in forthcoming talks on Kosovo's status.
Belgrade has long said it does not know his whereabouts, but some government figures have upheld foreign accusations that he is being sheltered by the Serbian and Montenegrin army.
Mr Draskovic said Belgrade could face international isolation unless it handed over Gen Mladic to the UN tribunal in The Hague by 20 November - the 10th anniversary of the Dayton peace accords that ended the Bosnian war.