BELGRADE - Radovan Karadzic's lawyer refused Saturday to give details of a last-minute appeal against the extradition of the former Bosnian warlord, who faces 11 charges at The Hague war crimes tribunal.

The Karadzic defence team had until midnight Friday to lodge a formal appeal. Proof of postage is sufficient even if the appeal has not yet arrived.

Lawyer Svetozar Vujacic was quoted by the Politika daily as saying the appeal was mailed from a post office, but he declined to say which one, so the letter could not be immediately identified and rushed to the court handling Karadzic's extradition.

But, speaking with reporters Saturday, Vujacic declined to give any details.

"I cannot say anything about the appeal, where or when I filed it or what is in it,'' he said. "Had I talked about it, the appeal would already be rejected and Radovan Karadzic would already be on his way to The Hague.''

Karadzic faces charges including genocide and conspiracy to commit genocide, for allegedly masterminding the 1995 slaughter of 8,000 Muslim men and boys in Srebrenica -- Europe's worst massacre since the Second World War.

Once Serb judges decide on the appeal, the case will be handed over to the Serbian government, which issues the final extradition order.

Karadzic was a fugitive for more than a decade before he was arrested. Government officials say he was captured Monday but Vujacic claims Karadzic was apprehended the previous week on a Belgrade bus and held incommunicado by unknown kidnappers for three days.

Vujacic has filed a lawsuit against Karadzic's alleged abductors. Responding to the lawsuit, a prosecutor spoke to Karadzic about the claims Friday, Vujacic said.

Vujacic says his client plans to defend himself against United Nations genocide charges, just as his mentor, former Yugoslav president Slobodan Milosevic, did. Milosevic died in 2006 while on trial on genocide charges.

In Serbia, Karadzic's arrest has sparked nationalist anger.

Several hundred ultranationalists -- chanting Karadzic's name and denouncing Serbian President Boris Tadic -- have marched daily in downtown Belgrade in support of Karadzic.

The demonstrators briefly scuffled with riot police Friday and hurled burning torches at the Belgrade City Council building.

More on Karadzic's fugitive period

Since his capture, more possible news on Karadzic's nearly 13 years under cover has emerged.

Serbia's Vecernje Novosti newspaper Saturday published an interview with Karadzic's nephew, Dragan Karadzic, claiming he was the only one who knew his uncle the fugitive had assumed the false identity of Dragan Dabic.

"I was his only link to the family and to the outside world,'' the nephew was quoted as saying, adding he regularly met with Karadzic, helped him with renting different apartments over the past six years and bringing him supplies.

"I am not afraid of the consequences,'' Dragan Karadzic said. "To me, he isn't a fugitive, he is my uncle, my father's brother.''

Vujacic, the lawyer, Saturday confirmed the nephew's claims, and added that a leading hardline priest of the Serbian Orthodox Church, Amfilohije Radovic, on Friday visited Karadzic in his prison cell.

Also Friday, Austrian police Col. Rudolf Golia said that anti-terror units found a man who looked exactly like the fugitive Karadzic's assumed identity while searching an apartment in Vienna for a murder suspect last year. The man was not connected to the killing, and he was let go without being fingerprinted.