"We have the right to demand full compensation from Ukraine, as we lost more than $2 billion during the first weeks of January," Alexander Medvedev, the deputy chief executive of Gazprom, told the Russia Today news station.
Medvedev added Bulgaria, which gets gas through Ukraine, had complained it would seek compensation from Gazprom for the disruption in gas supplies, though Medvedev placed the blame squarely on Kiev, RIA Novosti reported Monday.
Russia halted gas transits to Ukraine Jan. 1 after talks over gas contracts for 2009 and 2008 arrears collapsed. Europe gets 25 percent of its natural gas from Russia, and 80 percent of that volume transits through Ukrainian arteries.
Both sides reached a deal last week, though energy aides to Ukrainian President Viktor Yushchenko said Kiev could back out of the deal if undue influence was uncovered.
"The deal between (Ukrainian energy company) Naftogaz and Gazprom could be scrapped if it is found to have been signed under pressure," the president's top energy aide, Bohdan Sokolovskiy, said.