Serbs opposed to Kosovo's newly declared independence burned down a border post today.
Kosovo police manning the post on the border with Serbia called for help from the Nato peacekeeping force, Kfor.
"Protesters have destroyed the border crossing post at Gate 1 in Jarinje," a Kosovo police spokesman said. "No one has been injured."
Protesters were also attacking a second post at Zubin Potok in Kosovo's Serb-dominated north, he said. Police had taken shelter in a tunnel there as more than 1,000 protesters tried to tear it down, Kosovo police sources said.
"We asked Nato to send a helicopter to evacuate our officers," a police source said in Pristina. Kfor forces in the district include French, Danish, Belgian and American units. Kfor numbers some 17,000 troops.
"The border crossing post at Jarinje is on fire and the mob has dispersed," one eyewitness said. Albanian officers of the Kosovo police retreated and Serb officers crossed over into Serbia proper, police sources added.
Local Serbs backed by the Serbian government and Russia say the planned European Union supervisory mission to Kosovo, which will deploy 2,000 police and justice officials, is illegitimate and warn that its authority will not be accepted.
EU foreign affairs chief Javier Solana is expected in Kosovo later in the day to congratulate leaders on Sunday's independence declaration, recognised by most major Western powers but denounced by Serbia and Russia as illegal secession.
Earlier, US President George W Bush said his country recognised the independence of Kosovo from Serbia and said it would bring peace to the Balkans.
Speaking in Dar es Salaam, Mr Bush said the United States would soon establish full diplomatic relations with the new state. "We will work with the leaders of Kosovo to carry out a smooth and peaceful transition to independence," Mr Bush said.