Russian-British joint oil venture TNK-BP said Monday that tax authorities had levied a 610.4 million euros (US$792 million) back tax claim against it for 2001.
TNK-BP spokesman Peter Henshaw said the company, which is 50 percent owned by British oil giant BP PLC, disagreed with the claim and was trying to re-negotiate it.
"We received the claim late last week," Henshaw told Dow Jones Newswires. "This didn't come out of the blue. We've been working with the tax authorities on 2001 since December."
Earlier this year, members of Russia's upper house of parliament asked tax authorities to investigate TNK-BP, alleging that TNK had economized on its taxes by using onshore tax havens between 2000 and 2003 before its merger with BP.
The US$7 billion (5 billion euros) merger between TNK, which is controlled by tycoon Mikhail Fridman's Alfa Group, and BP's Russian oil assets went ahead to great fanfare in 2003 with the personal blessing of Russian President Vladimir Putin.
The deal was one of the largest ever by a Western company in post-communist Russia.