NATO says it is asking for additional troops for Kosovo after an escalation of violence in the country's ethnic Serb-dominated north last week.

A spokesman for NATO's Kosovo Security Force said Tuesday a battalion-sized force has been requested. He added that the reinforcements would act as relief troops for the soldiers currently deployed to maintain security.

NATO spokeswoman Carmen Romero says the situation has not gotten worse, but that the NATO troops have been very active and need to be relieved. The alliance currently maintains a force of 6,000 troops in Kosovo, nearly 12 years after the war that ended Serbia's rule there.

The most recent violence flared last week when Serbs in northern Kosovo confronted ethnic Albanian security forces, triggering an exchange of gunfire that killed one ethnic Albanian policeman and wounded several other people.

NATO peacekeepers intervened Thursday and took control of two border crossings under an agreement with the Kosovo government, which pulled out its special police. After the police withdrew, a mob of Serb attackers set fire to one border post and fired on NATO peacekeepers sent to quell the violence.

On Monday, Serbian officials met with a European Union mediator to discuss the latest bout of ethnic tensions in the region.

The head of Belgrade's negotiating team, Borislav Stefanovic, and Serbian Minister for Kosovo Goran Bogdanovic met Monday with EU envoy Robert Cooper in the southern Serbian town of Raska. Stefanovic said after the closed-door meeting that there would be more discussions, but he did not say when.