KIEV, Oct. 13 – Ukraine's state gas firm Naftogaz has officially asked Russia's Gazprom to amend a number of clauses from the gas contracts signed by the companies in January 2009, according to Bohdan Sokolovsky, the Ukrainian president's commissioner for international energy security.

He said on Tuesday that the two companies had held such talks for around two months.

"Naftogaz Ukrayiny submitted very concrete proposals on the amount of gas, the gas transit volume under another contract, and the price formation, i.e. the transit rate and the gas price," he said.