BELGRADE — Hundreds of riot police were deployed on Sunday evening as student-led protesters clashed with supporters of Serbia's President Aleksandar Vučić outside the parliament building in Belgrade.

Groups faced off on both sides of the police cordons with officers in full gear standing in several rows between the shouting crowds who threw bottles, flares and stun grenades.

At least 37 people were arrested overnight on Monday, including students, domestic media reported. One police officer was injured and a tent was set on fire, endangering the safety of those gathered, according to the interior ministry.

The ministry has asked the citizens to refrain from any acts of violence and not participate in unregistered gatherings that jeopardise the lives and safety of other residents or public property.

Tensions in Belgrade soared a day after tens of thousands of people joined a massive rally in the northern city of Novi Sad that marked the first anniversary of a train station awning collapse which killed 16 bystanders.

The disaster triggered a student-led movement demanding political changes, challenging the government in Belgrade.

The protesters in Belgrade on Sunday gathered in support of Dijana Hrka, the mother of Stefan Hrka, one of the Novi Sad awning collapse victims. Hrka said she was launching a hunger strike near a tent camp outside the parliament building which has been occupied by Vučić’s supporters since March.

Both police and Vučić said student-led protesters attacked his supporters' camp that he described as a “symbol of freedom". Protesters said those within the camp caused most incidents.

Protesters also gathered in Novi Sad and some smaller towns in support of Hrka.

They believe that alleged corruption during renovation work on the Novi Sad station building led to negligence and disregard of construction safety rules, and, consequently, to the collapse of the concrete awning onto people standing below.

Hrka said she was seeking accountability for the death of her son and the 15 other victims. She has also demanded that all detained protesters be released and that the president call a snap election as sought by the demonstrators.

Police have guarded the tent camp in front of the parliament building since it was set up in March. A shooting incident there last month which Vučić said was "an act of terror" has triggered fears of further escalation of violence. — Euronews