A worker turns a valve at an underground gas storage facility near Striy May 21, 2014. Russia has said state-controlled exporter Gazprom will not supply transit nation Ukraine with gas for its own use in June if Kiev fails to pay in advance and has warned a cut-off could affect supplies to European consumer nations via Ukraine. REUTERS/Gleb Garanich (UKRAINE – Tags: ENERGY POLITICS BUSINESS) – RTR3Q7Z6
