The international community's top official in Bosnia is seeking support from Yugoslav and Serb authorities in hunting down Radovan Karadzic and Ratko Mladic. Belgrade officials have been unwilling to arrest the two most-wanted Bosnian war-crimes suspects because they say it would spark a nationalist outcry among Serbs.

Wolfgang Petritsch, the tough-talking Austrian who is Bosnia's top international overseer, is impatient for the arrest of the two alleged war criminals.

Mr. Karadzic, who led Bosnian Serbs during the 1992 to 1995 war, and his military chief, General Mladic, have been indicted by the international war crimes tribunal in The Hague on charges of genocide.

Mr. Karadzic is believed to be hiding in mountainous eastern Bosnia, near the border of the Yugoslav republic of Montenegro.

Mr. Petritsch has in the past criticized the NATO-led Stabilization Force in Bosnia for doing too little to capture him. Last week, he said some countries with soldiers in the force feared any mission aimed at snatching Mr. Karadzic could wind up becoming a bloodbath. He did not name the countries.

General Mladic, on the other hand, is believed to be hiding in Yugoslavia. Chief war crimes prosecutor Carla del Ponte says he is in Belgrade and that he is protected by elements of the Yugoslav army.

Yugoslav President Vojislav Kostunica said General Mladic is not in Yugoslavia. And Serbian Prime Minister Zoran Djindjic said in an interview with the German magazine Der Spiegel that he is unwilling to send his police after General Mladic because any such hunt might lead to civil war in Serbia.

Mr. Petritsch, who said it is shameful that the two men are still at large, is frustrated at the reaction from Belgrade.

"It is still procrastination, which is not acceptable to the international community. I think I need to see greater activity on the part of the Serbian authorities, and this is going to be my message also to President Kostunica and to Prime Minister Djindjic," Mr. Petritsch said.

Mr. Petritsch said the fact that the two alleged war criminals are still at large hinders international efforts to achieve reconciliation in war-torn Bosnia, a country still divided along ethnic lines. Apparently resigned to inaction on the part of international peacekeepers to go after Mr. Karadzic, he is now insisting that local authorities hunt him down.

"I think it is an obligation on the part of the local authorities to go after alleged war criminals. It is not, in the first place, the international community's task. We want to see more local initiatives on this," Mr. Petritsch said.

The so-called Republika Srpska, which, along with the Muslim-Croat Federation, makes up postwar Bosnia, is the only part of the former Yugoslavia where not a single war-crimes suspect has been arrested by local authorities.

But the Bosnian-Serb government has passed a law on cooperation with the war crimes tribunal, and, this month, it urged all suspects hiding on its territory to give themselves up.