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.

Hundreds of thousands of people descended on Serbia's capital on Saturday to protest over the deaths of 15 people in a railway station collapse. 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.