RosUkrEnergo spokesman Andrei Knutov said on Monday Naftogaz's debt was over $2 billion, adding that the sum included "previous debts, and sums due for Russian gas consumed in 2008."
"As of July 1, Naftogaz Ukrainy's debt to RosUkrEnergo was within $897 million. This sum includes $650 million for gas imports bought by the company in June 2008. The debt is being paid regularly. The other claims are dubious and need to be clarified bilaterally," Naftogaz said.
Naftogaz also pointed to the Swiss trader's $141.8 million debt for gas transits from December 2007 through July 2008.
The Ukrainian company also accused RosUkrEnergo, co-owned by Russian energy giant Gazprom, of disrupting a shareholder meeting to decide on the payment of 2006-2007 dividends worth over $180 million to UkrGazEnergo, a joint venture of Naftogaz and RosUkrEnergo.
Russia and Ukraine agreed in March to simplify the gas supply system by getting rid of the Ukrainian UkrGazEnergo trader, but Russia insisted that RosUkrEnergo continue to be involved in the chain.
In early June it was reported that RosUkrEnergo had filed a lawsuit with the Stockholm Arbitration Court against Naftogaz, worth $55 million in fines for late payments in 2006.
The price for the natural gas Russia sells to Ukraine, and the transit fees levied by Ukraine on Russian gas pumped to the European Union, have proved a major source of contention since Gazprom began hiking prices to the country in 2005 after years of subsidized supplies.