Russian energy company Gazprom accused Ukraine of acting fraudulently by pursuing reverse shipments of European natural gas. Usually, most of Russia's natural gas for the European market heads west through the Ukrainian gas transit system.
"It's an absolutely legal and clean arrangement: gas crosses the Ukrainian border, so what questions can there be?" Makukha was quoted by the Interfax news agency as saying.
Gazprom Board Chairman Alexei Miller said Ukraine was getting its natural gas through third-party suppliers in Europe, which he said was fraudulent.
Ukraine has objected to a pricing scheme from Gazprom, saying it's more expensive than for most of its European counterparts. Fitch Ratings says it doesn't expect Gazprom to offer any relief.
"Miller's recent comments that its prices to Ukraine are rather moderate compared to current spot prices in Europe support this view," the ratings agency said last week. "We therefore believe that the prospects for a new gas price agreement ... are limited now unless accompanied by major concessions from Ukraine."