Serbian President Aleksandar Vucic says any deal with neighboring Kosovo to settle their long-standing disputes would need to include a guarantee of membership from the European Union.
"If we ever reach an agreement [with Kosovo], Serbia would need to get clear guarantees that it would become an EU member state in 2025," Vucic told Reuters in an interview published on September 13.
The EU has said that normalizing bilateral ties between Serbia and its former province is a key condition to move both countries toward EU membership.
Serbia lost control over Kosovo in 1999 after NATO bombed to stop the killing and expulsion of Albanians by Serb forces during a two-year counterinsurgency war.
Kosovo declared independence in 2008 and has been recognized by more than 100 countries, but not by Serbia.
The two sides in 2013 committed to EU-mediated talks to resolve their differences, but little progress has been made.
Vucic on September 8 said during a trip to northern Kosovo that he would be willing to continue talks with Kosovar officials but warned it will be difficult to reach a deal that could normalize relations.
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Serbia's President Addresses Serbian Minority In Kosovo
"I will do my best [to reach the agreement], but it is a long road full of thorns and problems ahead," Vucic said.
The Serbian leader's two-day visit to Kosovo came one day after a meeting between Vucic and Kosovar President Hashim Thaci was canceled after Vucic refused to meet.
Vucic told Reuters it could take up to 10 years for the two sides to reach an agreement because of all their differences.
"Sometimes I smile when I hear how people simplify things and say that the deal comes down to a line -- I will give you three villages and I will get six villages [in return]," he said.
He was referring to suggestions by some leaders of a possible land swap, whereby Serbia gave up areas with a majority ethnic Albanian population in return for Kosovar territory with a majority Serb population.
"If we were ever to reach a deal, it would have to be an overall deal that would include not only relations between us and the Albanians in Kosovo, but it would also have to include a resolution of our EU path and further economic progress," he said.
"Right now, we don't know where our borders are," Vucic said.
"No one in the region should be afraid of any agreement between Serbs and Albanians in Kosovo. The region will be more stable, stronger and economically more attractive," he said.
Although some EU and U.S. officials have said they support the exchange of territories, Germany and many analysts have said it is a bad idea that could renew old ethnic hostilities throughout the Balkans.