The situation has put pressure on Serbia's increasingly autocratic President Aleksandar Vucic, who has refused the protesters' demand to call an early parliamentary election.

Fresh clashes erupted between anti-government protesters and riot police across Serbia in the fifth night of unrest in a row, after offices of the the ruling Serbian Progressive Party (SNS) were set on fire.

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.