Four NATO peacekeepers have been wounded in a fight at a Kosovo-Serbia border crossing after weeks of tensions in the region.

Seven Serbs were also hurt in Tuesday's violence, which erupted when international forces began taking down Serb barricades at the disputed border point. Witnesses say NATO troops fired rubber bullets in self-defense at Kosovo Serbs, who threw stones toward the soldiers at the checkpoint.

Earlier this month, ethnic Serbs in northern Kosovo blocked roads leading to the border to protest a decision to put Kosovo customs officials at the crossing points in Brnjak and Jarinje.

Pristina, with the support of the United Nations peacekeepers and the European Union, has moved to extend its government control in northern Kosovo. Ethnic Serbs in that area have refused to recognize Kosovo's 2008 declaration of independence.

Belgrade considers Kosovo a part of Serbia and says it will not support the presence of Kosovo officials at the border crossings.

Two weeks ago, the United States called on both sides to refrain from inflammatory rhetoric and maintain calm.