In March, the office of TNK-BP was searched by Russian police.
Russian security services have searched the Moscow headquarters of oil giant BP - the second time in two months that that firm has been targeted.
The raid is reported to be linked to the firm's involvement with Gazprom.
In March, police raided BP's Moscow office and its TNK-BP joint venture, which employs 100,000 staff in Russia working on Siberian oil projects.
BP confirmed the latest investigation and said that it was co-operating with the authorities.
Foreign energy companies have come under increasing pressure in Russia as the government has been trying to increase its control over oil and gas assets.
TNK-BP was told last year that it was in danger of losing its production licence for a Siberian gas field for not meeting production targets.
The company eventually sold its stake in the Kovykta field to Russian state-controlled Gazprom.
Also last year Royal Dutch Shell was forced to hand over part of its stake in a massive Siberian gas field.