Audit Chamber chief Sergei Stepashin said the first overall inspection of Gazprom's books should be completed by November.
"Many speak of the closed nature of this company but I'd like to emphasize that Gazprom fully cooperates with the auditors of the Audit Chamber, providing them with all the necessary papers," he was quoted by news agency RT as saying.
Russian Federal Anti-monopoly Service accused Gazprom in 2011 of exploiting its dominant market position regarding access to a gas transportation system. Gazprom and Russian oil company Lukoil were fined by the FAS in 2008 for coordinating to fix the price of gasoline and diesel.
Full-year results reported in April by Gazprom revealed income for 2012 fell to $38 billion, its first loss since 2001.
Natural gas sales to European consumers were down 3.6 percent in 2012 year-on-year.
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