Leaders of Serbia, Yugoslavia's dominant republic, are demanding that Yugoslav President Vojislav Kostunica express support for the extradition of war crimes suspects to the international tribunal in The Hague, or else take full responsibility for what they say will be Yugoslavia's economic isolation. The demands come after Yugoslavia failed to meet a U.S. imposed deadline that freezes aid to Belgrade if it does not take concrete steps to cooperate with the tribunal.

There is an air of confrontation in Belgrade between the reformers who run Serbia and President Kostunica, who insists no Serb should be extradited to The Hague until Yugoslavia passes a law regulating extradition.

The reformers, led by Serbian Prime Minister Zoran Djindjic, are eager to modernize Yugoslavia's economy and integrate it into the European mainstream.

For that, they need massive doses of western aid to rebuild the war-torn country.

The U.S. Congress gave Yugoslavia until March 31 to hand over war crimes suspects or lose $120 million in financial assistance.

Mr. Djindjic says losing such American support would be a devastating blow for Belgrade, not only because of the loss of direct U.S. aid, but also because of Washington's influence at such international lending agencies as the International Monetary Fund and the World Bank.

Mr. Kostunica has expressed strong criticism of the war crimes tribunal, saying it is biased against Serbs. He says that, without a national law regulating extradition, the transfer of alleged war criminals to The Hague would destabilize Yugoslavia.

Many Serbs agree with the president. They see extradition of war crimes suspects as little more than trading people for money and, as such, an affront to Serbian dignity.

Mr. Djindjic, who engineered the extradition last year of former Yugoslav President Slobodan Milosevic to The Hague, over Mr. Kostunica's objections, was roundly criticized at home for taking such a step. He wants the president to share the political heat the next time a suspect is extradited instead of "scoring patriotic points" by publicly opposing such handovers.

Serbia's justice ministry has given police arrest warrants for four former close aides to Mr. Milosevic, who are accused of war crimes in Kosovo. But the willingness of police to arrest the men is open to question.

Seeking to shift the ball into the president's court, Serbian Justice Minister Vladan Batic says Mr. Kostunica must clearly spell out whether Yugoslavia is to cooperate with the tribunal or endure U.S. sanctions.