Thousands of people have protested in Serbia's capital Belgrade against the arrest of ex-Bosnian Serb army chief Ratko Mladic.

They hailed Gen Mladic as a hero and said he should not be handed over the UN's war crimes tribunal in The Hague.

There were clashes with police as the demonstration ended.The incidents started when a group of protesters threw rocks at police in Kneza Miloša St., who responded by "intervening against them", said reports, which mentioned that "at least one policeman was injured".

Police in riot gear pushed protesters back in several groups, while incidents occurred in several other locations in the city. Before they attacked police, the protesters lit flares, and threw bottles and other objects, shouting "go to Kosovo" at the officers.

More than 3,000 riot police were deployed around government buildings and Western embassies, fearing that the demonstration could turn violent. Riot police tried to block small groups of extremists from reaching the rally.

Police Director Milorad Veljovic said police in Belgrade were "completely in control of the situation".

The rally was interrupted when the violence started. The speakers previously pleaded for a peaceful gathering, and quoted a message sent on Saturday by Mladić himself, asking for calm after his arrest.

Police are currently out in force in downtown Belgrade.

By the time the crowds broke up by late evening, about 100 people were arrested and 16 minor injuries were reported.

Rioters overturned garbage containers, broke traffic lights and set off firecrackers as they rampaged through downtown. Cordons of riot police blocked their advances, and skirmishes took place in several locations in the centre of the capital.

Doctors said six police officers were among the 16 people brought to a hospital with minor injuries. Police remained on the streets as the crowds broke up.

Supporters of the extreme nationalist Serbian Radical Party were bused in to attend the rally. Right-wing extremists and hooligan groups also urged followers to appear in large numbers, creating the biggest test of Serbian sentiment and the government's resolve since Mr. Mladic's arrest.