Radovan Karadzic's lawyer has until midnight to file an appeal to the extradition order, Serbia's chief war crimes prosecutor has said.

The leader of the Bosnian Serbs in the 1992-95 Bosnia war, who is indicted twice for genocide, was arrested this week after 11 years in hiding, and is now held in a Belgrade prison.

Chief prosecutor Vladimir Vukcevic said Radovan Karadzic will be extradited to the United Nations tribunal in The Hague at the earliest on Monday.

The appeal may be sent in by post, which adds a small delay to the process.

"The panel of judges has three days to decide on the appeal, but I assume they will meet on Monday. Then the justice minister has to sign the extradition order."

Mr Vukcevic said that in theory, the panel of judges could accept Karadzic's appeal and reject the extradition order.

"However, it is highly unlikely," he added. "The earliest he can be extradited is Monday. We have no reason to rush. We have been waiting for him for 13 years."

Karadzic and his military chief Ratko Mladic were indicted in 1995 for planning the massacre of 8,000 Bosnian Muslims in Srebrenica and the 43-month siege of Sarajevo, where 11,000 people died from mortars, sniper fire, malnutrition and illness.

Karadzic has maintained his innocence, accusing the Hague court of being biased against Serbs.

Hardline nationalists agree, and have called a mass protest against his arrest and extradition.

Local media have reported that death threats were made against politicians blamed for his arrest, such as pro-Western President Boris Tadic.