Serb-dominated northern Kosovo remained tense Wednesday night after a group of masked men destroyed a border checkpoint to Serbia, DPA reported.
About 50 masked Serbs appeared at the Jarinje crossing in the evening, demolished the checkpoint with a bulldozer and set buildings on fire with Molotov cocktails, state broadcaster RTS reported. Gunfire was heard at the scene, but there were no immediate reports of casualties.
Soldiers of the NATO-led peacekeeping mission, KFOR blocked the area around Jarinje, RTS reported.
Jarinje is one of two checkpoints in northern Kosovo that the government in Pristina seized in a surprise police operation Monday.
The same compound was already torched once by Serbs, a day after Kosovo declared independence from Serbia in 2008.
The border's other crossing, Brnjak, remained calm.
In Belgrade, President Boris Tadic branded the Jarinje attackers as "extremists and hooligans" and urged Kosovo Serbs to remain calm.
The aim of extremists on both sides in Kosovo - Serb and Albanian - is to disrupt talks that Belgrade and Pristina launched under European Union auspices, Tadic said in a statement.
In Pristina, Prime Minister Hashim Thaci blamed the violence on "Serbia's parallel structures" in the north.
The EU law-enforcing mission, EULEX, had said even before the latest violence that it was "very concerned about the current situation in the north of Kosovo."
KFOR and EULEX said they have stepped up patrols in northern Kosovo to prevent a further escalation.
EULEX said it supports the effort of Kosovo authorities to assert themselves over the entire country but warned that it does not support unilateral steps.
Thaci's government had launched the raid on the border checkpoints without consulting EULEX.
Serbia, which insists on sovereignty over Kosovo, called an emergency United Nations Security Council debate on the situation in the former province. A meeting behind closed doors, not an open session as Belgrade sought, was scheduled for Thursday.
The recent violence has jeopardized the already fragile talks that Serbia and Kosovo launched in March under EU auspices.
While Albanians make up 90 per cent of the Kosovo population, Serbs vastly dominate the northernmost section. Backed by Belgrade financially and politically, they continue to resist efforts by Pristina to assert control over the area.
The EU-sponsored talks hit a wall last week, when Serbia refused to lift an de facto trade embargo on Kosovo goods, drawing a "reciprocal" measure - a ban of Serbian imports - from Pristina.
"There will be no compromise," Thaci told a late-night press conference. "There will be a reciprocity in trade relations with Serbia, ... and we will not revoke our decision on reciprocity."
The deadlock may dash Serbia's hopes of getting formal EU recognition as a membership candidate this year. European officials have said that Serbia needs to normalize its relations with Kosovo as a condition for membership.