Several thousand Serbian nationalists gathered in Belgrade on Sunday to protest against the arrest of Bosnian Serb wartime general Ratko Mladic.
A large number of the protesters arrived in Belgrade on buses from other Serbian towns.
Organisers of the rally, the Serb Radical Party (SRS), said they they did not expect incidents, stressing this was a peaceful protest.
The protesters carried SRS flags and photos of Mladic, Radovan Karadzic and Vojislav Seselj, all indicted for war crimes by the International Criminal Tribunal for the former Yugoslavia.
Some 3,000 police officers are securing the event.
Bosnian Serb wartime military leader Mladic, sought for genocide and war crimes during the 1992-95 Bosnian war, was arrested in Serbia last Thursday after 16 years on the run and is expecting extradition to the UN war crimes court in The Hague.
