Former Bosnian Serb army chief Ratko Mladic has called for calm following his arrest.
General Mladic was arrested in a village in northern Serbia on Thursday morning for the killing of an estimated 7500 Bosnian Muslim men and boys at Srebrenica in 1995.
He was also in command during the siege of Sarajevo which lasted 3.5 years during which 10,000 people died.
General Mladic, 69, has been declared fit to be extradited to the Hague to face trial, although his family and legal team say he is in poor health. He is to face charges of genocide.
General Mladic had been on the run for 16 years.
Lawyer Milos Saljic says his client has appealed to his supporters not to cause trouble.
''He is calling for there to be no bloodshed,'' said Mr Saljic after meeting General Mladic in his cell in Belgrade.
''He does not want to be the cause of unrest.''
A rally by the Serbian Radical Party is scheduled for Sunday in Belgrade.
The BBC reports right-wing groups have called for their supporters to join the rally outside parliament.
Serbian police chief Ivica Dacic said security has been tightened across the country.