Albanian police say 14 officers were injured during protests against new tolls being imposed on a road linking the country with Kosovo.
Thousands of residents gathered on March 31 in the northern town of Kukes to demand the cancellation of the tolls being imposed on drivers on the main artery between the two Balkan countries, both of which have ethnic-Albanian majorities.
Demonstrators threw stones and broke toll-collection boxes with bars and set fire to them.
The road fees range in price from 2.50 euros for a motorcycle to 22.50 euros ($27.72) for large trucks.
Albanian Prime Minister Edi Rama said the authorities would punish those carrying out violence against police officers and damaging property.
"The violators and those who inspired them should stop thinking they will triumph over the law," Rama said.
The Albanian leader said those who use the road, which crosses mountainous terrain, should help pay for it.
Many tourists from Kosovo travel to Albania for seaside locations. The 110-kilometer highway runs from Milot, near the Adriatic coast, to the border crossing at Morine.
Kosovar Prime Minister Ramush Haradinaj said the tolls were "excessive."
Kosovar truckers decorated their vehicles with banners saying, "This road should unite Albanians, not divide them."