A former British official has admitted for the first time that Britain did use a fake rock fitted with electronic equipment to spy on Russia.
Russia accused British diplomats in January 2006 of using the transmitter hidden in a Moscow park to receive intelligence from Russian agents.
The British government has previously declined to discuss the incident which first emerged in a Russian television broadcast.
Jonathan Powell, the chief of staff of then-Prime Minister Tony Blair, said in a BBC television documentary to be broadcast on January 19 that Russia had known about the hidden transmitter for some time and used it for political purposes.
Shortly after the incident was revealed, Vladimir Putin, Russian president at the time, introduced a law restricting all foreign funding for NGOs.
compiled from agency reports