NATO's peacekeeping force will do all it can to prevent tensions in Kosovo from escalating because of this weekend's election in neighboring Serbia, the alliance's top official said Friday.

NATO Secretary-General Anders Fogh Rasmussen said the force's "mission is to preserve a safe and secure environment for all people of Kosovo in an impartial way."

Serbia is holding a general election on Sunday. Tensions have intensified on the eve of the ballot as Kosovo sought to block voting in Serb-dominated northern Kosovo, saying these would undermine its sovereignty.

Kosovo unilaterally declared independence from Serbia in 2008. Belgrade has vowed never to recognize its secession. About 90 nations, including the U.S., support Kosovo's independence, though it is still not a member of the United Nations.

Serbia, which considers Kosovo the cradle of its statehood and religion, does not recognize Kosovo's independence. In addition, Serbs in the northern part of the former province do not recognize the government in Pristina, Kosovo's capital.

Kosovo's authorities, who are primarily ethnic Albanian, wield little authority in northern Kosovo.

The Organization for Security and Cooperation in Europe has agreed to oversee Serbia's presidential and parliamentary ballot in Kosovo, but not the local elections that some Serb officials want to organize, despite warnings from Pristina that force would be used to prevent them. Pristina says local elections would create a parallel administration on its territory.

"I strongly urge all leaders and all communities to show restraint during the voting process," Fogh Rasmussen said in a statement.

The NATO force was recently reinforced by a German-Austrian quick-reaction battalion, bringing its total strength to about 7,000 troops.

"I have full confidence in the judgment and professionalism of the (NATO commander) to use all the means within his mandate and all the instruments at his disposal, including the second battalion of the Operational Reserve Force," Fogh Rasmussen said.

The peacekeepers have been stationed in the landlocked nation since 1999, following a war that effectively ended Serbia's rule over its one-time province. The force originally numbered nearly 50,000 troops when it first entered Kosovo 13 years ago.

In a related development, police on Friday arrested eight people in Serbia's tense, ethnic-Albanian dominated south, five of them on suspicion of war crimes against Serb civilians during a 2001 conflict. The group was arrested in a police sweep in towns and villages in the region bordering Kosovo, said Interior Minister Ivica Dacic.

The arrests could fuel tensions in the volatile area and also in Kosovo. An ethnic Albanian politician from southern Serbia described the arrests as "state terror" against his community.