Turkey is to ask Russia to reduce the price of the natural gas it buys, the country's energy minister said on Thursday.Under an agreement between the two nations, each can request to negotiate a price change that reflects the market price. Ankara has the right to open negotiations on January 1.Energy Minister Taner Yıldız, who is attending 21st World Petroleum Congress in Moscow, said Turkey purchases 42 million cubic meters of Russian gas daily via the West Stream pipeline, which currently supplies 12.5 percent of Turkey's natural gas from Russia through Ukraine.If this supply was interrupted, Yıldız said, the 29 million cubic meters of natural gas Turkey buys from Iran and Azerbaijan would not be enough to meet the country's energy needs.Yıldız added that Turkey will continue to negotiate with Russia to increase the capacity of the Blue Stream pipeline by 3 billion cubic meters. He said Russia has pledged to complete the work by 2016. Russia sells 16 billion cubic meters of gas via Blue Stream and 14 billion cubic meters via West Stream to Turkey annually. Yıldız also said he would be talking to his Russian counterpart Alexandr Novak about Gazprom stopping gas supply to Ukraine and how this may affect the supply to Turkey.As a deadline for an agreement in European Union-brokered talks expired, Russia halted natural gas supplies to Ukraine on Monday, demanding that Ukraine pay in advance for the gas it imports from Moscow.