At least 100,000 people have converged in Belgrade for a massive rally in the Serbian capital seen as a culmination of months-long protests against populist President Aleksandar Vucic.

Serbian anti-corruption protesters, riot police, and supporters of President Aleksandar Vucic faced off in central Belgrade on Saturday as tens of thousands of people turned out for massive anti-government rallies following a night of sporadic clashes.

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.