Russian gas export monopoly Gazprom reduced supplies to Ukraine by a quarter on Monday but pledged its exports to Europe would not be affected, according to Reuters.

"Gazprom is a reliable gas supplier, but we cannot and won`t supply gas without payment," said Gazprom spokesman Sergei Kupriyanov. He said deliveries had been reduced by 40 million cubic meters a day.

Ukraine`s state energy firm, Naftogas, confirmed that supplies had been reduced, but gave a different figure of 30 mcm a day. It also said the reduction was not significant and would have no impact on consumers in Ukraine.