At least 10,000 people - many of them brought in by bus for the event - gathered in the main square of the central Serbian town of Kragujevac.

"After all the misfortunes that have befallen the Serbian people, every human, moral and state reason demands that the Yugoslav president step down," Mr Draskovic said.

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His supporters wore special t-shirts and waved flags in support of his Serbian Renewal Movement.

Mr Draskovic also called for the protection of Serbs in Kosovo.

"The authorities must rectify shameful things happening in Kosovo," he said. "Our people must feel safe and secure on their ancient land."

The rally came as the United Nations War Crimes Tribunal announced that Mr Milosevic may face new charges over his part in the wars in Croatia and Bosnia.

Mr Draskovic, who served a brief spell in government, shares the broad aims of the umbrella Alliance for Change, led by Zoran Djindic: the resignation of Mr Milosevic.

But - for the time being at least - he has decided not to throw in his lot with the other opposition parties.

War crimes investigations

At the end of a week-long Balkan visit, Louise Arbour - the chief UN war crimes prosecutor - said the tribunal was carrying out investigations that could lead to new charges being brought against the Yugoslav president.

Draskovic: We want, we demand his resignation

"I certainly expect that our ongoing investigations in Kosovo may lead to expanded charges against the persons who are currently indicted," said Mrs Arbour.

The Hague-based court has already ruled that Bosnian Serb forces were acting under Yugoslav control during the war in Bosnia, and charged Mr Milosevic for war crimes over the conflict in Kosovo.

KLA soldiers don uniforms

In Kosovo itself, the leader of the Kosovo Liberation Army, Hashim Thaci, has addressed a rally in the southern town of Orahovac in commemoration of KLA fighters who were killed during the conflict.

About 300 KLA members were granted special permission to wear uniforms for the occasion.

Jacky Rowland: "Vuk Draskovic relaunches himself as the heir-apparent to the Serbian throne."

Addressing the gathering, Mr Thaci said, "You were the essence of our war."

"Our job is not done yet. We have to be united more than ever for the independence of Kosovo, and the world must recognize our right for a referendum on independence."

Mr Thaci is currently the most popular of the Kosovo Albanian leaders.

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The new United Nations administrator for Kosovo, Bernard Kouchner, has meanwhile completed his first tour of the province, with visits to Pec, Prizren and Mitrovica - towns which saw severe ethnic violence during the conflict and where reprisals have taken place since.

Mr Kouchner said the burning of houses, threats and other acts of revenge against Serbian and other minorities would not be tolerated.