The court said Mladic, arrested on Thursday in a Serbian village, had until Monday to appeal against extradition to the international criminal tribunal in The Hague to be tried for a massacre in Srebrenica and the siege of Sarajevo during Bosnia's 1992-95 war.
European officials hailed his capture at a farmhouse belonging to his cousin also with the surname Mladic as a milestone on Serbia's path toward the European Union and said they expected his extradition within 10 days.
The U.N. Security Council also issued a statement welcoming Mladic's arrest and Serbia's plan to send him to The Hague.
His son, speaking after what he said was his first meeting with his father in years, said he was too ill. Last year the Mladic family asked a court to declare him dead to collect his military pension.
"We are almost certain he cannot be extradited in such condition," said Darko Mladic, a computer specialist by profession. "He is in very bad shape. His right arm is half paralyzed. His right side is partly numb."
His father, the once burly and aggressive Mladic, 69, moved slowly and with a slight limp when he appeared before an investigative judge at the special war crimes court in Belgrade on Thursday.
Mladic's lawyer later told reporters the court had halted the questioning because his client was "in a serious condition. He is hardly responsive." An official described him as looking disoriented and tired.
"Dead man arrested," ran several Serbian newspaper headlines on Friday, with a picture showing a pale and wizened Mladic, who is accused of instigating ethnic cleansing during the 1992-95 Bosnia war, Europe's heaviest fighting since World War Two.
Officials say Mladic has high blood pressure, heart disease and a kidney stone. His son said he had suffered strokes which had left two scars on his brain, although he said his father recognized the family and knew he was in detention.
Judge Maja Kovacevic said the medical team had determined he was fit for proceedings. "Mladic's lawyer was delivered the extradition papers and he has until Monday to appeal," she said.
Despite whatever ailments he may have had, Mladic was able to move frequently during his years as a fugitive.
Bruno Vekaric, Serbia's deputy war crimes prosecutor, said Mladic appeared in better shape during Friday's questioning.
"Mladic was making questions about his pension and sought it back. He also wanted a television set and Russian novels," he said, adding that he was under constant medical observation.
NO RESISTANCE
Mladic's lawyer Milos Saljic said he would appeal against the extradition on Monday and insisted that Mladic could not be handed over to The Hague until his health was stable.
"He must be provided with adequate treatment before the extradition," he told reporters.
Rasim Ljajic, the Serbian minister in charge of the search for fugitive war criminals, said Mladic -- often quoted saying "The Hague will not see me alive!" -- had not resisted arrest.
"Mladic had two loaded guns he did not use," Ljajic said.
"Mladic was dressed in several layers of clothes, he was hardly recognizable, he was not attracting attention. He looked pale as if he hadn't left confined spaces for a very long time," he said on Serbian television.
The deputy war crimes prosecutor said the court would continue to question the general, accused of orchestrating the brutal 43-month siege of the Bosnian capital and the massacre of 8,000 Muslim men and boys in the town of Srebrenica in 1995.
European Union foreign policy chief Catherine Ashton said she expected Mladic to be extradited to the International Criminal Tribunal for the former Yugoslavia (ICTY) in The Hague within nine or 10 days.
Mladic, whose Bosnian Serb Army was armed and funded by the late Serbian president Slobodan Milosevic, is still seen as a hero by many Serbs. Milosevic died in 2006 while on trial in The Hague for war crimes.
Nationalists in Serbia, which was under international sanctions over the war in Bosnia and then bombed by NATO to stop atrocities in Kosovo in 1999, condemned the arrest as a blow to national interests.
Several dozen rallied in Belgrade to protest, clashing briefly with police who dispersed them from the main square and the authorities increased security in certain areas of the country, including around foreign embassies.
Russia, which vehemently opposed the 1999 NATO bombing of Milosevic's Serbia and has accused the West in the past of bias against Bosnian Serbs, called for a fair trial for Mladic.
Chief war crimes prosecutor Serge Brammertz said it was impossible to say for how long the trial would last.
"It is clear that trials take often several years," he told reporters. "It is really difficult to give any timeline on this regard." The tribunal is scheduled to close down in 2014.
Croatia said it wanted to see Mladic's actions in Croatia in 1991 to be included in his indictment. He was a senior army officer in southern Croatia at the time and accused of crimes against civilians in the Croatian villages and towns.