Mon, 25 May 2009 20:10:04 +0200 (AFP/File) - A Naftogaz gas company worker adjusts valves at the Bobrovnytska gas compressor and holding station in the village of Mryn, about 130 km from Kiev, in 2008. The situation regarding Ukrainian payments for Russian gas is "very difficult", the head of Russian gas giant Gazprom, said Monday, Russian news agencies reported.(AFP/File/Sergei Supinsky)