Serb protesters in northern Kosovo blocked main roads for a second day on Sunday following a nighttime exchange of fire with police after the arrest of a former Serb policeman, amid rising tensions between local authorities and Kosovo's Serb minority.

In recent weeks Serbs in northern Kosovo have responded with violent resistance to moves by Pristina that they see as anti-Serb.

EULEX, the European Union mission tasked with patrolling northern Kosovo, said a stun grenade was thrown on one of its armored vehicles on Saturday evening, but no one was injured.

Josep Borrell, EU foreign policy chief, warned the bloc will not tolerate violence against members of its mission.

"#EU will not tolerate attacks on @EULEXKosovo or use of violent, criminal acts in the north. Barricades must be removed immediately by groups of Kosovo Serbs. Calm must be restored," he wrote on Twitter.

The latest protests were triggered by the arrest of a former police officer on Saturday. He was part of a mass resignation of Serbs from the force last month, after Pristina said it would require Serbs to scrap Serbian license plates dating to before 1999 when Kosovo was still under Serbian control.

For a second day on Sunday, trucks and other heavy-duty vehicles blocked several main roads leading to two border crossings with Serbia. Both crossings were closed to traffic.

Kosovo's head of government Albin Kurti has asked NATO's peacekeeping mission KFOR to remove the barricades.

"We call KFOR to guarantee the freedom of movement (and remove roadblocks)...KFOR is asking for more time to finish this ... so we are waiting," Kurti said.

Late on Saturday Kosovo police said they came under fire in different locations close to a lake bordering Serbia. The force said it had to return fire in self-defense. There were no reports of injuries.

Serbia's President Aleksandar Vucic presided over a National Security Council meeting on Sunday. "I call on Serbs to be calm. Attacks against KFOR and EULEX must not happen," Vucic told RTS national TV.

Kosovo unilaterally declared independence from Serbia in 2008. Serbia rejects it and considers Kosovo its own province. The two sides are holding talks in Brussels to try to normalize relations and the EU has already presented a plan.

(With input from Reuters)

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(Cover: Heavy vehicles parked by local Serbs block the road in the village of Rudare in northern Kosovo, December 11, 2022. /CFP)