Serbian President Aleksandar Vucic has announced tough measures against antigovernment protesters following days of riots challenging his rule.

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.

Serbia's president on Sunday vowed a "strong" response to anti-government protests, after nearly a week of violent clashes involving his supporters, police and demonstrators across the country.

Serbian police say nearly 50 protesters have been detained and dozens of people injured during clashes at anti-government protests in Serbia against the populist rule of President Aleksandar Vucic.

Serbia's police say they have detained scores of demonstrators who took part in anti-government protests throughout the country this week.

Angry protesters clashed with police in a town in western Serbia and in the capital Belgrade on Saturday as tensions soared further in the Balkan nation following days of violent demonstrations. Wearing scarves over their faces and chanting slogans against President Aleksandar Vucic,

The sometime actor and former Yugoslavian soccer player sold the eatery, which last year celebrated its 60th anniversary, to current owner Sonja Perencevic in 2009 before moving to Belgrade, Serbia.