BELGRADE, Serbia, Aug 17, (AP): Angry protesters clashed with police in a town in western Serbia and in the capital Belgrade on Saturday as tensions soared further in the Balkan nation following days of violent demonstrations. Wearing scarves over their faces and chanting slogans against President Aleksandar Vucic, a group of young men threw flares at his Serbian Progressive Party offices in Valjevo, some 100 kilometers (60 miles) from the capital Belgrade.

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. Similar clashes also erupted on Saturday evening in the northern city of Novi Sad and in Belgrade, with police directing tear gas at protesters while battling the protesters who set garbage containers on fire.

The protesters in Valjevo turned out to the streets to protest what they allege is police brutality. Interior Minister Ivica Dacic said at least one policeman was injured in Valjevo and 18 people detained so far. "There will be more detentions. All those who have broken the law will be arrested,” Dacic said. He said that the seat of the Valjevo court, prosecutor's office and the municipal building also have been demolished.

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. 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.

The protest in Valjevo drew several thousand people after a video on social media showed a young man from the town being severely beaten by police who kicked him and bashed him with batons during a protest earlier this week. The gathering was peaceful until groups of protesters threw flares at the SNS offices which sparked the fire inside.