Russian President Dmitry Medvedev has called on his Ukrainian counterpart Viktor Yanukovych not to politicize the Russian-Ukrainian gas cooperation, a Kremlin source said.
The two presidents met behind closed doors in the Russian Black Sea resort of Sochi on Thursday to discus bilateral relations, including Russian gas supplies to Ukraine.
"The Russian side stressed the necessity of observing the current agreements in the gas cooperation sphere," the source said. He added that the presidents agreed to "continue looking for new projects in this sphere."
The Ukrainian authorities believe that a gas deal concluded in 2009 by then-prime minister Yulia Tymoshenko is "disadvantageous" for Ukraine, and have long been seeking to review the contract's "unfair" price formula.
Russia has tied the price for gas to the international spot price for oil, which has been shooting up recently due to instability in the Middle East.
Tymoshenko, currently Ukraine's opposition leader, is now on trial over the signing of the contract, which the Ukrainian authorities say she did not have the right to sign since it was not approved by the government. Tymoshenko has denied the charges, saying that her trial is politically motivated. She faces up to 10 years in prison if found guilty.
The Russian Foreign Ministry said earlier this month that "all the deals on gas supplies were drawn up according to the legislation of the two countries and international law."
Ukraine's Prime Minister Mykola Azarov said last week that Kiev was considering taking the matter to a court of law to cancel the gas deal. But Yanukovych said ahead of Thursday's meeting with Medvedev that the two countries should seek an out-of-court settlement in their dispute.
In 2010, Ukraine's Naftogaz and Gazprom signed an additional gas agreement with a discount on Russian gas deliveries in exchange for permission for the Russian Black Sea fleet to berth in bases in the Crimea for 25 years after 2017, when the current base agreement expires.
Besides the gas issue, the Russian and Ukrainian president also discussed Ukraine's cooperation with the Customs Union of Russia, Belarus and Kazakhstan.
Ukraine has proposed joining the union as part of a "three plus one" format. The Kremlin source said this was "unacceptable" and the former Soviet republic should become a full-fledged member of the economic bloc.