KIEV, July 29 /ITAR-TASS/. The Stockholm Arbitration Tribunal has combined mutual claims filed by the Ukrainian national energy company Naftogaz and Russian gas giant Gazprom against each other into one case, Naftogaz CEO Andrei Kobolev said on Tuesday.

“The lawsuits have been combined to facilitate significantly the start of the process for examining the substance of the matter,” Kobolev said.

“A procedure for the appointment of arbitrators is currently under way. It will be over soon, after which the matter will be submitted for consideration,” Kobolev said, adding that a preliminary decision could be taken until winter.

“There are chances only for an interim decision. The nature of this decision will depend on the tactics we’ll choose. There are several options, which have been elaborated in detail and analyzed both with our lawyers and the Justice Ministry of Ukraine,” the Naftogaz head said.

Russia raised the gas price for Ukraine from $268.5 to $485.5 per 1,000 cubic meters from April 2014. Ukraine has said it will not pay for Russian natural gas supplies at such a high price.

After Russia and Ukraine failed to reach a compromise on the gas issue, Naftogaz and Gazprom filed mutual claims to the Stockholm Arbitration Tribunal.

The gas price for Ukraine has increased, in particular, by $100 per 1,000 cubic meters since April 1, 2014 after Russia denounced the 2010 Kharkov accords on extending the lease of the Russian Black Sea Fleet’s base in Crimea in exchange for a gas price discount. The accords were denounced after the Black Sea peninsula joined Russia in the spring of 2014.