Angry protesters clashed with police in the capital of Belgrade on Saturday as tensions soared further in the Balkan nation following days of violent demonstrations.

Serbia has been gripped by protests since November, when a train station canopy collapse killed 16 people.

Many blamed the tragedy on poor renovation work resulting from widespread corruption in infrastructure projects. 

The student-led protests had been largely peaceful for months but turned violent this week.

The situation has put pressure on Serbia’s increasingly autocratic president Vucic, who has refused the protesters’ demand to call an early parliamentary election. 

"Let the coward call elections, and if he loves his country, then he’ll deescalate the situation," said one protester, Marko Markovic, in Belgrade on Saturday.

"We all know that the situation will calm down when elections are called,” he added

Vucic has accused the protesters of following orders from abroad to “destroy Serbia,” and promised a crackdown on the nationwide movement led by university students. 

In Valjevo, some 100 kilometers (60 miles) from Belgrade, a group of young men threw flares at the Serbian Progressive Party offices, wearing scarves over their faces and chanting slogans against President Aleksandar Vucic.

They set fire to the party's offices before clashing with riot police in a downtown area. 

Police threw multiple rounds of tear gas and charged at the demonstrators who hurled bottles, rocks and flares at them. 

The protesters in Valjevo turned out to the streets to protest what they allege is police brutality.

There were no immediate reports on the numbers of injured people in either Valjevo or Belgrade.

AP Video shot by Marko Drobnjakovic