BRUSSELS, January 4 (RIA Novosti) - The European Union does not intend to support either party to the gas dispute between Russia and Ukraine, a deputy prime minister of the Czech Republic, which is currently holding EU presidency, said Sunday.

"We refuse to side with either party to this dispute. This is a commercial argument, we don't know all details of all contracts, which are confidential," Alexander Vondra was quoted by Radio Contact as saying.

Vondra called on the two countries to settle the dispute as soon as possible.

Russia cut off gas supplies to Ukraine on Thursday after last-ditch talks on Kiev's outstanding $2-billion gas debt and a new contract for 2009 failed late on New Year's Eve.

Some European countries, including Poland, Hungary, Bulgaria and Romania, have said that Russian gas deliveries through the Ukrainian pipeline have fallen.

Russian energy giant Gazprom's CEO Alexei Miller said Saturday Gazprom is to file a lawsuit with the Stockholm Arbitration Court against Ukraine's energy company Naftogaz to guarantee Russian gas deliveries to Europe across Ukraine.

Ukraine transits about 80% of Russian gas, a major source of revenue for Moscow, bound for the EU. Europe buys a quarter of its gas needs from Gazprom.

The 2006 gas row between the two former Soviet states resulted in a brief cutoff in supplies to Ukraine. When shortages were reported in some Eastern European countries, Russia accused Ukraine of siphoning off Europe-bound gas.