NATO and the European Union have condemned recent attacks by ethnic Serbs in northern Kosovo, as Serbia comes under pressure to end the unrest in the tense border region and secure its candidacy for EU membership.

In a statement Thursday, NATO's governing body said it was deeply concerned about the continuing attacks in northern Kosovo, adding that violence against peacekeepers is “unacceptable.” Clashes between NATO soldiers and Serb protesters have injured scores of people, including peacekeepers.

Serbs in the Kosovo-Serbia border region have been setting up roadblocks since July, when Kosovo's ethnic Albanian government tried to take control of the border area under de-facto Serb rule.

NATO welcomed Serbian President Boris Tadic's call Tuesday to remove the barricades on the northern border, but says the recommendation must be followed by concrete action. Violence broke out again Monday when Serbs fired on the peacekeeping forces as they tried to break down the blockades while using rubber bullets, water cannons and tear gas to disperse protestors.

NATO commanders said they will use lethal force if necessary to protect alliance troops, while Mr. Tadic urged the peacekeepers to stop using force to remove the roadblocks.

EU foreign ministers meeting in Brussels Thursday also denounced the violence, as representatives from Serbia and Kosovo met in the latest round of EU-brokered peace talks. European Union officials have said Serbia must find a resolution to the impasse if it wants its bid for EU candidacy to move forward.

The Serbs' blockades are cutting off NATO access to a military base in northern Kosovo. NATO is demanding freedom of movement throughout all of Kosovo.

The ethnic Serbs refuse to recognize Kosovo's independence, declared in 2008.