Rossiya via AFP - Getty Images

A combination of video grabs from footage broadcast by Russian state-run television in 2006 allegedly shows a man, said to be a British spy, in a park outside Moscow collecting a fake rock being used as a high-tech version of the spy's traditional letter-box or dead drop in which agents can anonymously deliver or retrieve information.

RTR via Reuters

Russian television said there was a transmitter inside the fake rock.

In an embarrassing episode for the British security services, Tony Blair's former chief of staff has admitted that the U.K. used a fake rock to spy on Russia. Reuters reports:

In a television program aired on Russian state television in 2006, Russia's FSB security service accused Britain of using the gadget for top secret communications in Moscow, but London did not admit to the charge at the time.

Now Jonathan Powell, who was chief of staff to then Prime Minister Tony Blair, has confirmed the Russians were correct.

"They had us bang to rights," Powell says in a BBC documentary to be aired on Thursday.

"There's not much you can say. You can't really call up and say 'terribly sorry about that and it won't happen again'," Powell says. Read the full story.

RTR via Reuters

Russian television showed an X-ray of what they said was a transmitter in the rock.