British spy chiefs secretly considered training pigeons to fly into enemy targets carrying explosives or biological weapons, it has been revealed.
British intelligence set up a "pigeon committee" at the end of World War II to ensure expertise gained in the use of the birds to carry messages was not lost.
Documents now released to the National Archives reveal that the War Office intelligence section, MI14, warned: "Pigeon research will not stand still; if we do not experiment, other powers will."
Among MI14's proposals was the training of pigeons carrying explosives to fly into enemy searchlights.
Meanwhile, pigeon enthusiast Wing Commander WDL Rayner suggested a "bacteriological warfare agent" could be combined with the explosive.
"A thousand pigeons each with a two ounce explosive capsule, landed at
intervals on a specific target, might be a seriously inconvenient surprise," Mr Rayner wrote.
He believed his "revolutionary" ideas could change the way wars were fought, and had the tentative backing of wartime MI6 chief Sir Stewart Menzies.
However the internal security service MI5 branded Rayner a "menace in pigeon affairs".
MI5's Lieutenant Colonel Tommy Robertson wrote: "I thought that some time ago it had been made clear that Rayner should finish writing his manual and then have nothing further to do with this committee officially."
Rayner's plan for a 400-pigeon loft where tests would be carried out was abandoned due to wrangling among the intelligence agencies over funding.
Members of the public can view the 280 newly-released files at the National Archives, Kew, west London.