The Bush administration said Thursday it is withholding another $10 million in aid committed to Serbia and Montenegro because of that country's poor record on helping the Balkans war crimes tribunal.  Similar action was taken last year.

The decision reflects growing U.S. frustration over the failure of authorities in Serbia and Montenegro, and also in the ethnic-Serb republic in Bosnia-Herzegovina, to apprehend indicted war crimes fugitives.

State Department Spokesman Richard Boucher, in a written statement, said Secretary of State Colin Powell has decided to withhold $10 million in U.S. aid to Serbia and Montenegro for the 2005 fiscal year.

He cited what he termed a continuing record of non-compliance by the Belgrade government with regard to its obligations to the U.N. war crimes tribunal at The Hague.

The U.S. Congress approved a three-year $100 million economic aid package in 2002 to help Serbia and Montenegro recover from the Balkans war and damage wrought by the former Yugoslav government of Slobodan Milosevic.

But Congress made the aid contingent on periodic certifications by the U.S. administration that Belgrade is adequately supporting the Hague tribunal, and there have been several interruptions in aid distribution as a result.

Spokesman Boucher said the latest $10 million is in addition to $16 million that remains withheld after Mr. Powell declined to certify in March of last year that Serbia and Montenegro were cooperating with the court.

He said the United States calls on authorities in Belgrade to cooperate fully with the tribunal by arresting and transferring fugitive indictees to face justice in The Hague, particularly former Bosnian Serb military chief Ratko Mladic.

The spokesman said Mr. Powell is prepared to review the decision if future actions by Belgrade demonstrate support for the court.

In the meantime, Mr. Boucher said the Bush administration is examining alternative ways to use aid earmarked for Serbia and Montenegro by re-directing it away from the central government to groups committed to reform.

Ratko Mladic and wartime Bosnian-Serb leader Radovan Karadzic, both facing charges for the killings of thousands of Bosnian Muslims a decade ago, are the most prominent of several Balkans war crimes figures still at large.

The Bush administration has in recent weeks also been sharply critical of the compliance record of the ethnic-Serb republic in the Bosnian federation, imposing financial sanctions against Bosnian-Serb political parties and companies.

The International High Representative for Bosnia-Herzegovina, Paddy Ashdown, last month fired several police and other officials of the Republika Srpska.

Mr. Ashdown cited evidence that Ratko Mladic had recently been sheltered at a military bunker complex in that area.