Tens of thousands of anticorruption protesters have taken to the streets of Serbia’s capital, Belgrade, demanding an early election in a bid to end the 12-year rule of President Aleksandar Vucic.

Large numbers of officers in riot gear were deployed to police Saturday’s protests, which were organised by Serbia’s university students.

The students were a driving force behind nationwide demonstrations that started nearly eight months ago after the deadly collapse of a renovated concrete rail station roof in the northern city of Novi Sad killed 16 people.

The tragedy last November became a flashpoint for frustrations with the government, with many Serbians saying that it had been caused by alleged corruption and negligence in state infrastructure projects.

Under pressure, Prime Minister Milos Vucevic resigned at the start of this year, but Vucic remains in power.

Serbia’s railway company halted train service over an alleged bomb threat in what critics said was an apparent bid to prevent people from travelling to Belgrade for the rally.

Hours before the rally at Slavija Square and Nemanjina Avenue, Vucic’s party sent in buses of its own supporters from other parts of the country, many wearing T-shirts reading: “We won’t give up Serbia”.

They were joining loyalists who have been camping near Vucic’s office in central Belgrade since mid-March.

Vucic, a populist whose Progressive Party-led coalition holds 156 of 250 parliamentary seats, told reporters on Saturday that unspecified “foreign powers” were behind the protest. He said police should be restrained, but warned that “thugs will face justice”.

Vucic has previously refused snap elections and has been intent on continuing his second term, which ends in 2027, when there are also parliamentary elections scheduled.

But his hold on power has been rattled, with opponents accusing him and allies of ties to organised crime, violence against rivals and curbing media freedoms – charges they deny.

Earlier this week, police arrested several people accused of allegedly plotting to overthrow the government and banned entry into the country, without explanation, to several people from Croatia and a theatre director from Montenegro.