Serb ultranationalists clashed with police during a rally in Belgrade Tuesday to protest the arrest and likely war crimes trial of former Bosnian Serb leader Radovan Karadzic.

Witnesses say hundreds of young men they describe as "hooligans" broke away from the main rally to throw rocks at police, who responded with tear gas and rubber bullets. No serious injuries are reported.

Police say about 15,000 people rallied in Belgrade's main square in support of the jailed Karadzic - far short of the 100,000 who had been expected.

Serbian Radical Party leader Aleksandar Vucic said thieves and bandits are running Serbia.

Some in the crowd called Karadzic a hero who saved Serbian lives during the Balkan wars of the 1990s.

Karadzic is currently in a Belgrade jail waiting for his extradition to The Hague for trial at the U.N. war crimes tribunal.

The tribunal has charged him with genocide for his alleged part in the 1995 slaughter of 8,000 Muslim men and boys in Srebrenica.

Karadzic was one of the world's most wanted fugitives when he was arrested last week in Belgrade after 12 years on the run. He had assumed a new identity, heavily disguised his appearance, and practiced alternative medicine. He faces a total of 11 charges of genocide and war crimes.

Karadzic's lawyer, Svetozar Vujacic, is appealing his extradition. But the Belgrade court has yet to receive the documents.

Meanwhile, European Union ambassadors have put off action on granting improved trade conditions to Serbia until authorities in Belgrade hand over Karadzic to the U.N. tribunal.

Some information for this report was provided by AFP and AP.