Opposition leader and former Ukrainian Prime Minister Yulia Tymoshenko is on trial for corruption stemming from a 2009 gas deal she helped broker to get Russian gas company Gazprom to resume disrupted supplies. Kiev argues the deal hurt the country financially and has pressed Moscow for a better price formula. Tymoshenko denies the charges filed against her.
Ukrainian Prime Minister Mykola Azarov, who had said he was ready to go to court over the issue, said he still hopes to secure a discount peacefully.
"We are still focused on holding a negotiation process with Russia," he was quoted by Russia's state-run news agency RIA Novosti as saying. "I am still a supporter of a normal negotiation process, based on equality and respect so that our partners listen to our arguments."
Ukraine, meanwhile, has been examining the potential of its shale natural gas reserves. U.S. supermajor Exxon Mobil signed a preliminary deal with Naftogaz early this year and Ukrainian Energy Minister Yuri Boiko said he was expecting shale gas auctions soon.