Chanting "Treason!" and "Let's rise up!" about 15,000 supporters of Slobodan Milosevic rallied Monday to protest the former Yugoslav president's extradition to the U.N. war crimes tribunal.

The rally, held in front of the federal Parliament by supporters of Milosevic's Socialist and allied ultra-nationalist Radical party, was the biggest of three pro-Milosevic protests organized since his extradition on Thursday.

"Our ancestors are ashamed of you, you'll all go to hell," said one of the banners directed at Serbian government. The protesters demanded new elections and chanted "Slobo, we'll get you back!"

Zoran Djindjic, the Serbian prime minister behind Thursday's sudden extradition, has said that all other Serb suspects living in Yugoslavia — believed to number about a dozen — will soon join Milosevic in The Hague, Netherlands where the tribunal is located.

Serbia is by far the larger of the two remaining republics in Yugoslavia and effectively determines Yugoslav policies, despite the existence of a separate, federal Yugoslav government.

Serbian officials, speaking privately, say their republic is ready to provide evidence on demand from the tribunal.

But such cooperation would have to be low-key. A federal decree on working with the war crimes court was ruled unconstitutional by a high court, and Milosevic's handover was made possible by a one-time Serbian government order that does not address the broader issue of cooperation with the tribunal past his extradition.

The Yugoslav Left party, led by Milosevic's wife Mirjana Markovic, denounced his extradition.

"Because of the kidnapping by the Serbian government, the government ministers and those who gave orders will one day certainly face the judgment of a real court — the one of the people and the history," her neo-communist party said in a statement.

As Milosevic's supporters rallied in Belgrade, his lawyers arrived in the Netherlands to prepare him for his first appearance before the war crimes tribunal Tuesday, and former U.S. Attorney General Ramsey Clark offered to help defend him.

Milosevic was handed over to the tribunal last week to face war crimes charges for atrocities committed by Serb troops in Kosovo during the 1998-99 war in the Serb province.

About 10,000 Kosovo ethnic Albanians are believed to have been killed during Milosevic's crackdown against their pro-independence rebellion.

On Monday, Kostunica held talks with other Serb pro-democracy leaders about appointing a new Yugoslav Cabinet following the resignation of the Yugoslav prime minister, Zoran Zizic, over the extradition.