Serbian President Boris Tadic in Moscow on Wednesday inked a multimillion-dollar energy deal with his Russian counterpart Dmitry Medvedev, according to dpa. Under the deal, Serbia will sell a controlling stake in its oil monopoly NIS to Russian state giant Gazprom in exchange for a share in a strategic Russian pipeline through Serbia. Serbian media reported the 51-per-cent stake was sold for 400 million euros (560 million dollars). Gazprom will also invest a further 550 million euros in the modernization of NIS's refineries and the construction of a gas storage facility in northern Serbia, media said. Routing of the 13-billion-dollar South Stream pipeline through Serbia, carrying Russian gas under the Black Sea to Western Europe, would secure the country supplies and transit fees. Russian President Dmitry Medvedev called the signing ceremony "an event that marks the advent of a new era." Russia, a long-time ally of Serbia, backed Belgrade's opposition to the breakaway province of Kosovo's unilateral declaration of independence. Tadic said Serbia would always be open to Russian investments. Serbia "lies halfway between Russia and the European Union," he said in televised comments. "We are seeking to join the EU, and this will also be useful for Russia, now with the signing of this contract we will become part of an enormous energy project," he said. But the sale of NIS caused a rift among Serbian lawmakers. Economy Minister Mladjan Dinkic protested, saying that the price was too low and that the Russians gave no guarantees that the South Stream gas line would go through Serbia. Igor Sechin, Russia's deputy prime minister for energy, downplayed concerns telling journalist the deal "guaranteed the Serbian side that all three energy projects would be carried out.