Serbia's refusal to impose sanctions on its ally Russia remains the main obstacle to a speedier European Union accession bid, Prime Minister Ana Brnabic said on Friday, describing the move as the "condition above all conditions" set by the bloc.
Serbia has long performed a delicate balancing act between its European aspirations, partnership with NATO and its centuries-old religious, ethnic and political alliance with Russia.
After a speech marking 100 days of her cabinet, Brnabic said that Serbia had made progress in EU membership negotiations but that this was not sufficient for Brussels.
"It seems ... that the level of alignment with common foreign and defence policies of the European Union, hence introduction of sanctions on the Russian Federation, is a condition above all conditions," she told reporters.
To join the EU Serbia must first complete membership negotiations, normalise ties with Kosovo, its former ethnic Albanian province, and align its foreign and defence policies with those of Brussels, including placing sanctions on Russia over its invasion of Ukraine.
Although it has repeatedly condemned Russia's invasion of Ukraine in the United Nations and other international forums, Serbia has been criticised by Brussels for not formally introducing sanctions against Moscow.
Last December, Serbian President Aleksandar Vucic said Serbian authorities had clamped down on those who attempted to bypass sanctions against Russia through Serbia.
Russia is Serbia's main ally in its opposition to the independence of its former province Kosovo which declared independence 15 years ago, nearly a decade after NATO bombing drove Serb forces from its territory.
Serbia is also entirely dependent from gas imports from Russia and country's NIS oil producer also majority-owned by Gazprom Neft and Gazprom. Belgrade wants to diversify its gas supplies.
Serbia also maintains military cooperation with Russia as its weaponry is loosely based on ex-Soviet technology.
(Reporting by Aleksandar Vasovic; Editing by William Maclean)