A Russian spy has disclosed the art behind his craft from behind bars

A hollow rock was used by the CIA to give cash to a policeman in Moscow who passed secrets to the Americans about Russian security services.

Yevgeny Chistov, 34, said that he used “dead drops” around the city to hand over information on police and intelligence officers and employees of the Federal Protective Service (FSO), which guards Mr Putin and other high-ranking officials.

No details were released when Chistov was sentenced in 2015 to 13 years in a penal colony for treason after a closed trial. He has now disclosed the spycraft he used in an interview from behind bars with the Meduza website.

In 2014, FSB officers seized him as he was packing a suitcase to flee to Thailand after a tip-off that he