"We are not going to pay it," a high-ranking Ukrainian official source told AFP, asking not to be identified and refusing to give any further comment. Ukraine's state energy firm Naftogaz confirmed over the weekend that it has received the bill from Gazprom, which comes at a time Kiev is bracing for budget trouble amid an economic slowdown. The bill was presented as the the ex-Soviet state signed a landmark $10-billion shale gas production sharing agreement with global oil giant Royal Dutch Shell in Kiev's most ambitious move to limit its dependence on Russian gas. A dispute between Kiev and Moscow over gas prices and bills in early 2009 prompted Gazprom to cut gas supplies to Kiev and leave parts of Europe without energy amid a bitterly cold winter.