The international community Thursday announced new measures against Bosnian Serb officials for failing to hand over indicted Balkans war crimes figures to the U.N. tribunal in the Hague. They include targeted sanctions by the United States, which criticized "obstructionism" by the semi-independent Bosnian Serb republic.

The coordinated action by the United States, the International High Representative for Bosnia Paddy Ashdown, and European Union peacekeepers in Bosnia reflects frustration that key Balkans war crimes figures remain at large.

Mr. Ashdown, overseer of the 1995 Dayton accords on the Balkans conflict, announced the firing of six Bosnian Serb police officers and three other officials for failing to arrest war crimes suspects or obstructing the process.

The U.S. ambassador to Bosnia, Douglas McElhaney, appearing with Mr. Ashdown at a Sarejevo news conference, said U.S. financial and travel sanctions were being imposed against Bosnian Serb political parties and officials.

European Union peacekeepers, meantime, raided an underground bunker complex once used by former Bosnian Serb military chief Ratko Mladic.

Ratko Mladic, along with wartime Bosnian Serb leader Radovan Karadzic, is accused of genocide and crimes against humanity in the Balkans conflict. They are the most prominent of several war crimes figures still at large.

At a news briefing, State Department Spokesman Richard Boucher said the United States is committed to do everything it can with international partners to locate the fugitives, and to isolate those who seem to be supporting and hiding them. "The essence of this is that we are acting in concert with these other entities. We are acting to impose restrictions on the Serbian party leadership that we think had been colluding with Mladic, Karadzic, these kind of people, to protect them," he said.

The U.S. sanctions include a travel ban against the leadership of two major Bosnian Serb political parties, the Party for Democratic Progress and the Serb Democratic party, or SDS, which was founded by Radovan Karadzic.

The measures also freeze any assets the parties may have in the United States and bar Americans from financial dealings with them. In addition, the U.S. Treasury Department added three companies and six individuals to a financial blacklist of persons and entities deemed to be impeding the Dayton accords.

In a written statement, spokesman Boucher said the United States remains committed to helping Bosnia-Herzegovina "assume its rightful place" in the Euro-Atlantic community, but said elements within the Bosnian Serb republic are impeding progress toward that goal.

He said the "Republika Serbska" hasn't arrested a single war crimes indictee in nine years, and that its failure to cooperate fully with the Hague tribunal is a "fundamental breach" of the Dayton Accords.

Mr. Boucher said it is clear that "systemic" changes in the police and security structures of the Republika Serbska are needed to "overcome this obstructionism."

Post-war Bosnia-Herzegovia is made up of two semi-independent entities, the Serb republic and the Muslim-Croat Federation, with a central government in Sarajevo in which power is shared among the three main ethnic groups.