Russia and Ukraine traded arguments on Monday about fees paid to transit gas to Europe, raising fears of a repeat of a conflict that led to a two-week stoppage of gas supplies to Europe last January, according to Reuters.

The disagreement came just after a meeting between Russian Prime Minister Vladimir Putin and his Ukrainian counterpart in which Moscow said it would let Kiev off fines for not buying as much gas as promised.

Russian President Dmitry Medvedev told the chief executive of gas export monopoly Gazprom, which supplies a fifth of Europe`s gas needs via Ukraine, not to agree with Kiev to change gas transit fees, Russian newswires reported.

"We need to act in line with the (January) agreement which was reached ... It was a big strain and a lot of work, and we need to implement it," Medvedev told Gazprom CEO Alexei Miller, according to Interfax news agency.

But Ukrainian state energy firm Naftogaz shortly after the report said that according to the January deal, the transit fees that Gazprom must pay were subject to change and directly linked to the import price of gas used for transit.

"According to the agreement with Gazprom, the price for the fuel (technological) gas is a component in the transit rate and a rise in that technological gas (price) causes a rise in the transit fee," said a Naftogaz spokesman.

Last week, Gazprom said it expected gas transit fees via Ukraine to rise by up to 59 percent in 2010, against Ukraine`s expectations of a maximum 60 percent increase.

Kiev and Moscow have often disagreed over gas prices and supplies, including the transit of Russian gas across Ukraine, and such a dispute led to gas supplies to Europe being severed for more than two weeks in January.