Nato has condemned attacks by demonstrators in Kosovo that left some 25 of its peacekeepers injured, describing it as totally unacceptable.
Police and Nato troops clashed with Serb protesters in the north where there has been unrest over the installation of ethnic Albanian mayors.
Tear gas and stun grenades were used to deter protesters in Zvecan after they tried to invade a government building.
The crisis dates back to April when Kosovo Serbs boycotted local elections, allowing ethnic Albanians to take control of local councils with a turnout of less than four percent.