Ethnic Serbs in northern Kosovo have blocked all roads leading to border crossings with Serbia to protest a decision to place Kosovo's customs officials on the border crossing between Kosovo and Serbia.

Many have spent the night on the barricades made up of rocks and gravel. Serbia's top Kosovo negotiator Borislav Stefanovic met with local residents Saturday and called for calm.

The European Union mission in Kosovo used helicopters Friday to place Kosovo's forces and customs officials at the border posts in Brnjak and Jarinje.

The governments of Serbia and Kosovo, urged by the European Union, are negotiating for a peaceful resolution of the tensions.

Pristina insists on extending the government control in northern Kosovo, which has refused to recognize its 2008 declaration of independence. Ethnic Serbs who are the majority in the region remain loyal to Belgrade and reject ethnic Albanian administration.

Belgrade considers Kosovo a part of Serbia and says it will not support the presence of Kosovo officials at the border crossings. But officials say they want a peaceful solution to the border dispute. The two sides are set to hold another meeting in Brussels at the end of the month.

An attempt by Pristina in July to take over the border posts led to violence in which one person was killed. NATO peacekeepers restored peace and took temporary control of the crossings.

A debate on Kosovo Thursday at the United Nations Security Council in New York ended without a resolution.

The United States Friday called on both sides to refrain from inflammatory rhetoric and maintain calm. A spokesman for the State department, Mark Toner, said the barricades impair the daily lives of people on both sides of the border.