"We are cooperating with the investigation, which is not impeding the office's work," Vladimir Buyanov said.
Police have not commented on the search, and no information on the nature of the investigation has been released.
The Moscow BP office was raided by police in mid-March. Police also seized documents from the central office of TNK-BP, half-owned by the British company.
Security officials said papers on oil and gas production believed to contain commercial secrets, as well as ID cards belonging to foreign military organizations and to the CIA were found during the searches of TNK-BP.
Federal Security Service officers detained TNK-BP's Ilya Zaslavsky on March 12, along with his brother Alexander, who has links with the British Council, for industrial espionage aimed at giving foreign oil and gas companies illegal advantages.
