Srdjan Ilic, Associated Press
Rioters clash with police in Belgrade, Serbia, Tuesday after a rally in support of war crimes suspect Radovan Karadzic.

BELGRADE, Serbia — Authorities began extraditing ex-Bosnian Serb leader Radovan Karadzic to the war crimes tribunal to face genocide charges early Wednesday, an official with the Serb prosecutor's office said, despite a violence-tinged protest hours before by thousands of his supporters.

Four jeeps with tinted windows were seen speeding away from the downtown Belgrade war crimes court at about 3:45 a.m. Wednesday where Karadzic was being held since his arrest July 21.

An official of the prosecution office told The Associated Press that Karadzic was in one of those jeeps on his way to Belgrade airport from where he will be flown to the U.N. court in the Netherlands. The official spoke on condition of anonymity because she was not authorized to speak to the media.

Karadzic was captured last week in Belgrade, where he lived under the assumed identity of a health guru, with long white beard and hair, and large glasses.

Karadzic faces 11 charges at the U.N. tribunal in The Hague, including genocide and conspiracy to commit genocide.

Late Tuesday night, a demonstration against just such a move turned violent on its fringes as stone-throwing extremists clashed with police, who responded with tear gas and rubber bullets.

While most of the 15,000 demonstrators sang nationalist songs and waved posters of their "Serb Hero," a few hundred hard-liners broke away from the gathering and threw rocks and burning flares at police in downtown Belgrade.