Russian authorities have summoned the chief of a British-Russian joint energy venture in Moscow for questioning, as part of a tax evasion probe.

The firm TNK-BP, in a statement, Thursday said the questioning of Robert Dudley is related to tax matters from 2001 to 2003. The firm's billionaire Russian shareholders, Len Blavatnik, Mikhail Fridman and Viktor Vekselberg, last week demanded Dudley's ouster. It remains unclear whether the two developments are related.

Russian Police Summon Chief of British-Russian Energy Venture in Tax Probe

The summons follows police raids last month on TNK-BP offices in Moscow, and a similar raid in March. Two people with dual U.S.-Russian citizenship were arrested in the March raid on suspicion of industrial espionage.

Russian Police Summon Chief of British-Russian Energy Venture in Tax Probe

In 2007, TNK-BP was forced to relinquish its 63 percent interest in a huge gas project in Siberia to the Russian state-run natural gas giant, Gazprom.

Russian Police Summon Chief of British-Russian Energy Venture in Tax Probe

At that time, energy analysts compared the BP situation to Gazprom's forced 2006 takeover of the giant Sakhalin-two project in Russia's Far East. A Western consortium led by Royal Dutch Shell agreed to sell its controlling interest in the Sakhalin project, after Russian threats of huge lawsuits against the consortium for alleged environmental infractions.