Two NATO soldiers and three Serbs were wounded Friday when the troops clashed with a crowd trying to stop them removing barricades put up by Serbs in north Kosovo, sources on both sides said.
The German army, the Bundeswehr, said that the wounded soldiers were German nationals hit by gunfire, one in the arm and the other on an ear, while a Serbian official said the troops had used rubber bullets and tear gas.
"KFOR confirms two wounded soldiers during the removal operation of Rudare roadblock (Friday) morning," the NATO-led peacekeeping force in Kosovo, KFOR, said in a statement.
"One wounded soldier has been evacuated. He is in a stable condition," KFOR added, without giving details of their injuries.
The Bundeswehr said the soldier with the ear injury had been treated on the spot.
Oliver Ivanovic, Serbia's state secretary for Kosovo, told Tanjug news agency three Kosovo Serbs were hurt when KFOR troops moved in to disperse several hundred people protesting at the barricade's removal.
The clash over the Rudare roadblock is the latest in a series in the flashpoint area of northern Kosovo since last year.
Political analyst Predrag Simic said the KFOR action was a message to Serbia's new president, nationalist Tomislav Nikolic, who was sworn in this week.
"I think this is a heated welcome for a new president but also a message to Belgrade that things in Kosovo have gone too far," he told Beta news agency.
Media in Belgrade reported that Nikolic met with top officials of the outgoing cabinet to discuss the incidents in Rudare but no official statements were released immediately.
Serb officials said about 150 KFOR soldiers were deployed in the area where local Serbs had set up the roadblock to prevent ethnic Albanian Kosovo police and customs officials from entering the Serb-populated area.
The barricade in Rudare was on the road leading to the Jarinje border crossing between Serbia and its breakaway southern province, which is manned by KFOR.
The situation on the ground remained tense, an AFP journalist reported as local officials urged several dozen remaining protesters to stay calm following earlier reports that they threw stones at the NATO troops.
"Let them remove the blockade, we must not let anyone be hurt," Zvecan mayor Dragisa Milovic told the crowd, warning that the KFOR troops were "ready to shoot."
Serbia's Minister for Kosovo Goran Bogdanovic also called on all sides to show restraint.
"Each side should restrain from making risky moves. Any escalation of the conflict can lead us into a spiral of violence with unforeseen consequences," he told Tanjug.
Kosovo's minority Serbs, who do not recognise its declaration of independence in 2008, began setting up road blocks to prevent Pristina's ethnic Albanian police and customs officials from manning the northern border posts.
Clashes ensued and in November some 50 KFOR soldiers were hurt as they moved to dismantle barricades.
Most were removed in February as EU-sponsored dialogue between Belgrade and Pristina was revived.
Out of a population of about two million, there are some 120,000 ethnic Serbs in Kosovo, with 40,000 in the north on the border with Serbia and the rest in enclaves dotted around the territory.
Kosovo has been recognised as an independent state by more than 80 countries, including the United States and most EU members.