Tens of thousands of people swarmed the streets in Serbia's capital Belgrade on Friday, staging a joyful prelude to a major anti-government rally on the weekend and dealing a blow to populist President Aleksandar Vucic.

Huge crowds are converging on downtown Belgrade for a major rally against populist President Aleksandar Vucic and his government

While the government put attendance at 107,000 across Belgrade, an independent monitor said 325,000 - if not more - had gathered, making it Serbia's largest protest ever. The Novi Sad collapse last November has galvanised anger towards the government and President Aleksandar Vucic.