Bulgaria's Prime Minister Kiril Petkov on Wednesday described Russia's decision to halt gas supplies to the EU member as "blackmail."

The move on the part of Russian energy giant Gazprom "is a gross violation of the contract and blackmail... We won't give in to such racketeering," Petkov said, adding that Bulgaria, for its part was reviewing all contracts with Gazprom, including the contract for transit through the Balkan country.