BELGRADE (Bloomberg) -- Serbian Prime Minister Vojislav Kostunica told political parties to reject European Union membership unless Kosovo's declaration of independence is overturned and the province is restored to the Balkan state.

“I call on everyone to confirm the policy which Serbia has been conducting for years in the defense of its essential interests and to state clearly that Serbia will go into the EU only with Kosovo as its constituent part,” Kostunica said in Belgrade, according to a statement on the government's Web site.
Kosovo has a central place in Serbia's history and culture. The majority ethnic-Albanian region has an estimated 130,000 Serbs scattered along the northern and eastern borders with Serbia and in isolated pockets.
While Kostunica is leading calls for the annulment of Kosovo's independence declaration, President Boris Tadic has said Serbia's struggle to keep the province within its borders shouldn't harm its bid to join the EU. Tadic was sworn in for a second term last month.
Parties must “confirm unity on the political position that Kosovo is an integral part of Serbia and Serbia wants to enter the EU in its entirety,” Kostunica said.
U.S. Assistant Secretary of State Daniel Fried told the Senate Foreign Relations Committee there is a danger Serbia may turn away from Europe and “choose the path of self- isolation” after Kosovo's independence declaration gained widespread recognition from western countries.
“The United States has a strategic interest in Serbia finding its way to Europe. But Serbia must put aside politics of nationalism,” Fried said, according to a transcript.
“Serbs feel very strongly that Kosovo should not be independent. But after that, you get a split,” he added. “They want to go to Europe.”
EU leaders have promised Serbia eventual membership, counting on Tadic to reconcile the country of 7.5 million people to the loss of Kosovo.
Kostunica earlier this year rejected a political agreement offered by the EU aimed at pre-empting a nationalist backlash over Kosovo. The accord would have begun moves toward visa-free travel for Serbs and promoted economic and educational exchanges.
Serbia lost control of Kosovo, a province of 2 million people, when the North Atlantic Treaty Organization began a bombing campaign in 1999 to drive out Serb forces accused of waging an ethnic-cleansing campaign in the province.
The area has since been administered by the United Nations as an international protectorate.
Border police from the UN Mission in Kosovo, or UNMIK, reasserted control of a rail line in northern Kosovo, a day after Serbian Railways claimed control of it in a challenge to the region's independence.
The intervention “reverses the challenge to UNMIK's authority” that occurred when “Serbian Railways illegally sent two of its trains south of Lesak” in northern Kosovo, Joachim Rucker, head of UNMIK, said in a statement on the UN Web site.