NATO troops have taken control of two customs posts on Kosovo's northern border with Serbia, after they were attacked Wesdnesday by Serbs armed with firebombs. A NATO spokesman says only small vehicles are being allowed to pass through the border posts, and each is being checked for weapons.

The posts had been taken over by special police units of Kosovo's ethnic-Albanian government in an operation earlier in the week in which one policeman was killed. Kosovo was attempting to enforce a ban on imports from Serbia in retaliation for its block on Kosovo's exports.

The Kosovo police withdrew from the crossings Wednesday following an agreement negotiated by NATO.

Serbia's president, Boris Tadic, said Wednesday's attack was conducted by hooligans, and he urged Kosovo Serbs to remain calm.

A government spokesman in Belgrade said Serbia had addressed the United Nations Security Council, where “consultations” on Kosovo should take place later Thursday.

Kosovo declared independence from Serbia in 2008, but the 60,000 Serbs who live in northern Kosovo still consider Belgrade their capital.

The European Union has criticized Kosovo for not coordinating the border post operation with the international community. European Union-mediated talks between Kosovo and Serbia have made little progress in reconciling the two sides. Serbia has banned the entry of goods from Kosovo since 2008.