Thousands of students descended upon the central Serbian city of Kragujevac on Saturday in what was expected to be the biggest show of anger yet against the government over a deadly railway disaster in November.

In the three months since 15 people were killed when a roof collapsed at a newly-renovated train station in the city of Novi Sad, mass anti-corruption demonstrations have spread across the Balkan state to become Serbia's biggest protest movement in years.

Many Serbians blame the tragedy on corruption and nepotism within President Aleksandar Vucic’s government, which denies the allegations. Political analysts say the demonstrations have created one of the biggest threats to populist Vucic's decade-long grip on power.

On Saturday morning in near-freezing temperatures, students arrived in Kragujevac from across Serbia, by bus and even on foot from the capital Belgrade some 140 km away, beating drums, blowing on whistles and holding up the country’s flag. Locals greeted them with applause.

The protesters planned to blockade one of the city’s main boulevards for 15 hours and 15 minutes, in a symbolic tribute to the victims.

“We are here to fight for a better tomorrow, against corruption,” said 20-year-old Jovan, who drove from Belgrade with a group of friends. “I love my country and I want my children to grow up here,” he said.

Prime Minister Milos Vucevic and two other ministers have resigned over the protests and prosecutors have charged 13 people over the disaster, but this has done little to quell the demonstrations.

Since the accident, students have staged daily protests, taking over university buildings and blocking highways and squares.

“We will stay here until the blockade ends,” said Djordje Vujovic, 22, a mechanical engineering student.

“We want to be able to continue our studies but only when our demands are met,” he said.

The students are demanding that authorities publish documents relating to the station roof collapse; justice for those responsible; the dismissal of charges against protesting students; and a greater budget for higher education.