Twenty-five NATO peacekeepers have been injured in a clash with Serbs protesting recent election results in northern Kosovo.
Since Friday, the peacekeepers, known as Kosovo Force (KFOR), have been assisting police in protecting four municipal buildings from ethnic Serb protesters in the north.
The tense situation in Kosovo developed after ethnic Albanian mayors took office in northern Kosovo's Serb-majority area following elections that the Serbs boycotted.
The peacekeepers said they were attacked with incendiary devices by protesters in the town of Zvecan.
"While countering the most active fringes of the crowd, several soldiers of the Italian and Hungarian KFOR contingent were the subject of unprovoked attacks and sustained trauma wounds with fractures and burns due to the explosion of incendiary devices," KFOR said.
"The unprovoked attacks on NATO units are unacceptable and KFOR will continue to fulfil its mandate impartially."
According to AP, soldiers fired tear gas and stun grenades to protect Kosovan officers and disperse protesters.
The Serbs responded by throwing rocks and other hard objects at them.
Some Kosovo police vehicles and one belonging to journalists were damaged and defaced with Serb nationalist symbols.
Serbs, who form a majority in Kosovo's north, have never accepted its 2008 declaration of independence from Serbia.
The group still see Belgrade as their capital over 20 years after the Kosovo Albanian uprising against repressive Serbian rule.
Serbia has also refused to recognise an independent Kosovo.
Serbs demanded the Kosovo government remove ethnic Albanian mayors from town halls and allow local administrations financed by Belgrade to resume their work.
Addressing the nation late Monday, Serbian President Aleksandar Vucic said he would spend the night with his troops on the border with Kosovo who were placed on the highest state of alert on his orders last week.
According to AP, he said 52 Serbs were injured in the clashes, three seriously, and four were detained.
"The consequences (of the clashes) are big and grave and the sole culprit is (Kosovo Prime Minister) Albin Kurti," he said.
"I repeat for the last time and I beg the international community to make sure Albin Kurti sees reason," Mr Vucic said.
"If they don't, I am afraid it will be too late for all of us."
On Twitter, Mr Kurti condemned the attacks against KFOR, local police and journalists.
"We stand for peace and security," he said.
