A former top British official has admitted for the first time that Britain spied on Russia using electronic equipment inside a phony rock.

Jonathan Powell told the BBC that British spies were clearly responsible for the espionage attempt in Moscow six years ago.

He said Russia had known about the spy plot for some time and was saving it up for a “political purpose.”

Russian television broadcast video in 2006 of what appeared to be British officials placing or retrieving an imitation rock on a Moscow street. The footage exposed communications equipment inside the rock intended to store data to be downloaded by British officials.

Vladimir Putin, Russia's president at the time, used the plot to justify new restrictions on non-governmental organizations. Russian officials accused Britain of paying human rights groups in hopes of stirring discontent against the government.

At the time of the attempted plot, Powell served as chief of staff to then-British Prime Minister Tony Blair.

Britain's Foreign Ministry declined to comment on Powell's remarks.