NATO-led peacekeepers on Friday exchanged fire with angry Serb protesters seeking to prevent international troops from removing roadblocks in Kosovo's tense north, leaving four rioters and two alliance soldiers wounded.

The bloody clash revived tensions in the Serb-controlled area, where Kosovo Serbs who reject Kosovo's 2008 declaration of independence from Serbia set up roadblocks last year to prevent the ethnic Albanian government in Pristina from extending control over the region. While some of those roadblocks have since been removed, a few still remain in place.

The latest incident took place near the town of Zvecan, where NATO-led troops blocked a bridge with armored vehicles and barbed wire as they moved to remove a roadblock.

NATO's mission in Kosovo, or KFOR, said two German soldiers were wounded when Serbs fired at them with sniper shots, and the troops responded with live ammunition.

"KFOR responded in self-defense today, using teargas, rubberbullets and also live ammunition," NATO spokesman in Kosovo Lt. Col. Uwe Nowitzky told The Associated Press. He said the bullets were used because "we spotted clearly and identified a sniper pit, and actually the sniper has been deactivated by direct live ammunition fired by our soldiers."

"KFOR condemns this act of violence," Nowitzky said. "KFOR will not allow the situation to escalate and will use a proportional level of force necessary to maintain a safe and secure environment."

KFOR said in a statement that it started removing the roadblocks to "improve freedom of movement" for both its troops and the citizens. The statement said that the troops set up numerous temporary check points and secured areas for safety reasons.

In Brussels, EU spokeswoman Maja Kocijancic said "we are very concerned about the current situation in northern Kosovo."

"We urge everybody to show restraint and cooperate with international institutions in Kosovo," Kocijancic said, stressing the EU's support for "the basic principle of the freedom of movement."

Kosovo Serbs have vowed never to allow Kosovo's authorities to impose their rule in the north. Last year's tensions led to clashes that left dozens of NATO peacekeepers injured and slowed down Serbia's bid to move closer to European Union membership.

EU officials have brokered talks between Serbia and Kosovo. Belgrade has refused to recognize the independence of its former province, although Kosovo's statehood has enjoyed backing from the United States and most EU nations.

Kosovo's President Atifete Jahjaga condemned violence against NATO in a statement and blamed it on Serb "illegal structures" seeking to obstruct freedom of movement. Jahjaga backed KFOR's "action to prevent the rule of anarchy" in the Serb-populated north.

In Serbia, the top security body, the National Security Council, said in a statement issued after an urgent meeting on Friday that "the security of the citizens (of Kosovo) has been seriously jeopardized." The council also urged restraint, saying that "dialogue, and not violence, are the only way toward stability in the region."

Serbia's National Security Council comprises top government and security officials. Friday's session was headed for the first time by the new, nationalist president Tomislav Nikolic.

Oliver Ivanovic, a Serbian government official dealing with Kosovo, criticized KFOR's decision to remove the roadblocks, saying it revives tensions amid efforts to reopen the EU-mediated talks. Ivanovic warned that "this is very dangerous and could escalate."

Serbia lost control over Kosovo after a war in 1998-99, which ended after NATO intervened to stop the bloodshed. About 10,000 people, mostly ethnic Albanians, were killed in the conflict.


Jovana Gec and Dusan Stojanovic in Belgrade, Serbia, Florent Bajrami in Pristina, Kosovo, and Don Melvin in Brussels contributed to this report.