The offices of the the ruling Serbian Progressive Party (SNS) have been set on fire during a fifth night of unrest in a row that saw fresh clashes between anti-government protesters and riot police.

Violence escalated across Serbia as anti-government protests entered their fifth consecutive night. In Valjevo, masked protesters set fire to the ruling Serbian Progressive Party (SNS) offices before clashing with riot police.

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.