Serbian police have clashed with a huge crowd of anti-government protesters demanding an early election and end to President Aleksandar Vucic's 12-year rule in the capital Belgrade, BBC reported.

A sea of around 140,000 protesters rallied in the city, the largest turnout in recent months, as student-led demonstrations mount pressure on the populist government. "We want elections!" the crowd chanted.

Dozens have been arrested, with riot police seen firing tear gas and stun grenades.

President Vucic accused protesters calling for an election of being part of a foreign plot trying to usurp his country. "They wanted to topple Serbia, and they have failed," he wrote on his Instagram page, according to BBC.