Thousands of demonstrators gathered last night in the Serbian capital Belgrade to protest against President Aleksandar Vucic and the government, the Associated Press reported, quoted by BNR.
The agency estimates the number of demonstrators at tens of thousands, and the protest at "Slavia" Square in the city center - one of the largest in recent years.
The protest is now part of a broader movement demanding accountability for the collapse of the canopy at the Novi Sad train station on November 1, which killed 15 people.
Today's demonstration was called by students and farmers' organizations.
Smaller demonstrations were held in Niš and Kragujevac.
The protest in Belgrade began with a 15-minute silence in memory of the victims of the Novi Sad tragedy, followed by chants of "There is blood on your hands!".
Many in Serbia blame the tragedy on corruption and shoddy construction work at the station, which has been renovated twice in recent years as part of a controversial project involving state-owned Chinese companies.
Yesterday, Vucic opened a newly built highway section in central Serbia and said he would not give in to opposition demands for a transitional government.
He accused his opponents of using students and pupils to try to seize power. "We will defeat them again. They (the opposition) don't know what to do except use someone else's children," Vucic said.
Opposition parties are demanding a transitional government to prepare new elections.
Classes at many universities have not been held for weeks, and students have occupied their faculty buildings.
In recent days, many students have joined the protests, and the government has decided to start the winter break earlier in an attempt to deal with the student movement.