NATO has deployed peacekeepers in the north of Kosovo after a border post with Serbia was burnt down and a Kosovo policeman killed. Serbian nationalists in Kosovo attacked the post on Wednesday after Kosovo's government sent police to enforce a ban on imports from Serbia. Border posts in the area, which rejects Kosovan independence from Serbia, had been staffed by ethnic Serb police. Kosovo's government suspected them of turning a blind eye to banned imports. NATO officials said only small vehicles are being allowed through two border posts at the centre of the dispute and that they were being checked for weapons.Serbian police Chief Milorad Veljovic told newsmen that Serbia has also reinforced police on its side of the border to prevent extremists from Serbia going to Kosovo.