Ukrainian energy company Naftogaz has filed a 1.52 million hryvna ($187.5 million) suit against former Prime Minister Yuliya Tymoshenko, who is now under a criminal investigation for signing a 2009 gas contract with Russian gas export monopoly Gazprom, Naftogaz representative Igor Kost said on Friday. Kost said the claim corresponded to the losses incurred by Naftogaz as a result of the deal, adding he was acting on behalf of state-run Naftogaz's chairman. The 2009 contract tied the price for gas supplied by Gazprom to oil prices and Ukraine's bill has been increasing since. The new government, which came to power after the presidential elections at the start of 2010, has been negotiating new terms ever since. Tymoshenko, who narrowly lost to current President Viktor Yanukovich, faces up to 10 years in prison on charges of abuse of power while in office. She denies any wrongdoing. The court adjourned the hearings until July 18.