RUSSIA     -   Secrets of Cold War spy-pigeons have been revealed after the CIA declassified sensitive files from the time.

The files from the 1960s and 70s reveal how pigeons were trained for clandestine missions photographing sensitive sites inside the Soviet Union.

The release also reveals how ravens were used to drop bugging devices on window sills and dolphins were trained for underwater missions.

The CIA believed animals could fulfil “unique” tasks for the agency’s clandestine operations behind the Iron Curtain at the height of tensions between Russia and the US.The secret files are stored at the CIA’s headquarters in Langley, Virginia, is a museum, which is not open the general public.

The 1970s’ operation, codenamed Tacana, explored the use of pigeons with tiny cameras strapped to their bodies to automatically take photos, the newly released files show.

It took advantage of the fact that the humble pigeon can be dropped somewhere they have never been before andhave the amazing ability to find their way hundreds of miles back home.

The use of pigeons for communications dates back thousands of years but it was in World War One that they began to be used for intelligence gathering.