TENS of thousands streamed into a central square in Serbia’s capital today for a rally against populist President Aleksandar Vucic and his government, whose tight grip on power has been challenged by weeks of street protests led by university students.

The rally at Belgrade’s Slavija Square, one of the largest in recent years, was called by students and farmer unions. It was part of a wider movement demanding accountability over the November 1 collapse of a canopy at a railway station in the country’s north that killed 15 people.

Smaller rallies were also held in the cities of Nis and Kragujevac. The rally in Belgrade started with a 15-minute silence for the victims, and later chants of “You have blood on your hands!” were heard.

Many in Serbia blame the collapse on widespread corruption and sloppy work on the railway station building in the city of Novi Sad, twice renovated in recent years.

Protesters are demanding that Mr Vucic and those responsible face justice.

Serbia’s popular theatre and film actors joined the protest, with actor Bane Trifunovic describing today’s rally as “a festival of freedom.”

But in a show of confidence, the Serbian president inaugurated a section of a newly built highway in central Serbia today.

Mr Vucic said he wouldn’t budge on opposition demands for a transitional government and accused his opponents of using students to try to seize power.

“We will beat them again,” said Mr Vucic.“They [the opposition] don’t know what to do but to use someone’s children.”

Prosecutors have arrested 13 people over the Novi Sad tragedy, including a government minister whose release later fuelled public scepticism about the honesty of the investigation.