Serbian police have fired tear gas at anti-government protesters in downtown Belgrade as they clashed for the third day on the streets of the country's capital and other cities amid reports of police brutality and excessive use of force during the unrest.

President Aleksandar Vucic is facing accusations of sending hooligan groups to suppress the anti-corruption movement that has shaken the country for the past nine months.

Serbia's police used teargas and crowd control vehicles on Friday evening in Belgrade to disperse anti-government protesters who threw firecrackers and flares at police officers in what is seen as a major escalation of the nine-month-long protests.