Gazprom says Ukraine's debt has built up since November 2007
Russian gas monopoly Gazprom has warned Ukraine it will reduce its gas supplies from next Monday if a $1.5bn (

EU Energy Commissioner Andris Piebalgs called on both sides to find a solution as soon as possible.

On Wednesday, Ukraine joined the World Trade Organisation after 14 years of negotiations. Russia is the world's only major economy not to be a member.

Ukraine's gas imports were already high on the agenda for a summit in Moscow next week involving Russian President Vladimir Putin and Ukrainian President Viktor Yuschenko.

But Mr Kochevrin insisted the dispute was not political in any way.

"We're a commercial company: our investors won't understand if our profits fall," he said.

"We're accused again and again of political bias. I can assure you there is no political bias. Our link to the Kremlin is only through our management board."

Gazprom says the $1.5bn debt is made up of $1bn accrued from Central Asian exports at the end of 2007 and a further $500m of Russian gas piped to Ukraine in January 2008.