BELGRADE, Serbia - Radovan Karadzic hopes to defend himself against UN war crimes charges, his lawyer said Wednesday, raising the prospect that one of Europe's most wanted men will use the courtroom to preach Serb nationalism and rewrite the history of the Balkan wars.

Bruno Vekaric, spokesman for Serbia's war crimes prosecutor, said the former Bosnian Serb wartime leader's extradition to the UN war crimes tribunal at The Hague, Netherlands, "could be Monday or Tuesday -- but it could be earlier, too."

Karadzic is wanted on 11 charges, including genocide and crimes against humanity for allegedly leading ethnic cleansing campaigns against Croats and Muslims in the 1992-1995 Bosnian war. The psychiatrist-turned-Serbian-nationalist is accused of masterminding the deadly wartime siege of Sarajevo and the 1995 executions of some 8,000 Muslim boys and men in Srebrenica.

He was captured Monday in Serbia after more than a decade on the run and is in a Belgrade cell awaiting extradition to The Hague.

"He can't wait to appear before the court," his lawyer, Sveta Vujacic, told reporters. "He will have a legal team that will help him, but he will defend himself."

Karadzic has 30 days after his transfer to enter the pleas. If he refuses, judges will automatically enter not guilty pleas on his behalf.

Vujacic has said he would resist extradition. A 72-hour period for Karadzic to launch a formal appeal expires on Friday, Vekaric said.

Vujacic said Karadzic intends to defend himself during his upcoming trial at the UN tribunal, with the help of a team of legal advisers, just as the late Serbian strongman Slobodan Milosevic did. Milosevic died in 2006 while on trial in The Hague.

The court's spokeswoman, Olga Karvan, said Wednesday that prosecutors "believe the interests of justice will be best served if the accused are assisted by qualified counsel."

The arrest of Karadzic, one of world's most-wanted men, was hailed by the U.S. and by European governments who applauded Serbia's new pro-Western leadership for the capture.

But in Belgrade, dozens of Serbian nationalists took to the streets Tuesday, clashing with police during a protest in the capital.

Chanting "Treason!," the demonstrators threw stones and clay pots at riot police who cordoned them off. Five demonstrators and a policeman were injured, doctors at a Belgrade emergency clinic said.

"This is a hard day for Serbia," Tomislav Nikolic, leader of the ultranationalist Serbian Radical Party said. "(Karadzic was) a legend of the Serbian people."

Nikolic vowed his party will do "all in its power" to topple the pro-Western government.

Serb officials say they arrested Karadzic on Monday evening near Belgrade. Karadzic had grown a long, white beard to conceal his identity and had lived freely for months in the capital before he was captured.

"His false identity was very convincing," said Vladimir Vukcevic, Serbia's war crimes prosecutor who coordinated the security forces arrest. "He had moved freely in public places."

While on the run in Serbia, he worked at a private clinic and wrote for a Belgrade magazine, according to Serbian officials.

To do all this, Karadzic used a false name -- Dragan Dabic -- government minister Rasim Ljajic told reporters Tuesday. Ljajic displayed a recent photo of an unrecognizable Karadzic with long, bushy white beard and gray hair.

Ljajic refused to reveal more details about Karadzic's arrest, saying his movements were being analyzed to help track down another top war crimes suspect still at large, Bosnian Serb wartime commander Ratko Mladic.

Karadzic appeared to be arrested because of a change in political will.

Serbian President Boris Tadic's pro-Western government came to power only two weeks ago and appointed a new security chief, replacing an aide to former nationalist prime minister Vojislav Kostunica.

European Union foreign ministers said the arrest helped Serbia's bid for membership in the bloc, and German Chancellor Angela Merkel hailed Karadzic's capture as a "historic moment."

Karadzic's whereabouts had been a mystery since he went on the run in 1998; his early hideouts reportedly included monasteries and mountain caves in remote eastern Bosnia.

Karadzic's family in Bosnia, barred from leaving the country because of suspicions that they helped him elude capture, has asked to have those restrictions lifted, his daughter told The Associated Press.

More than 100,000 people died during Bosnia's war, and 1.8 million others were driven from their homes.