Britain considered using chickens to trigger nuclear land mines in a bizarre scheme to shore up its defences during the Cold War.

Military chiefs planned to use the explosives to devastate Soviet forces if they forced the western Allies into retreat during an invasion of Europe.

But designers feared the bombs would become too cold if they were buried underground during a winter war, meaning they would not explode.

Their improbable solution was to place chickens inside the mine - nicknamed Blue Peacock - using their body heat to keep the nuclear weapon working.

The seven-tonne nuclear land mine, codenamed Blue Peacock, which Britain planned to use against a Soviet attack and for which a bizarre plan was developed using chickens

A top secret document from 1957 discussing the nuclear land mine plans, spelling out the fears of military chiefs that the weapon might not work in the cold during a winter invasion of Europe

The chickens would have enough food for eight days and would then starve, meaning they could function as a primitive timer.

A 1957 document, not revealed to the public until 2004, said that 'chickens, with a heat output of the order of 1,000 BTU (British Thermal Units) per bird per day are a possibility.'

The plan sought to hold up Soviet invaders if they breached the Iron Curtain and attacked West Germany.

Research by David Hawkings, published in the journal Discovery, unearthed details of the secret nuclear land mine plan.

Britain planned to make 10 of the mines and position them with the British Army in West Germany to counter a feared Soviet attack.

Tests on the 16,000-pound weapon were to be explained away by saying it was an 'atomic power unit for troops in the field', the research found.

Research by David Hawkings (pictured), published in the journal Discovery , unearthed details of the secret nuclear land mine plan known as 'Blue Peacock'

The mushroom cloud after a nuclear explosion. Britain planned to make 10 of the mines and position them with the British Army in West Germany to counter a feared Soviet attack

However the mine was scrapped in 1958 after just two prototypes had been manufactured, and was never used.

Military chiefs are said to have been reluctant to place nuclear weapons in allied countries, fearing the possible fallout.

The Cold War plans were hatched after the first UK nuclear bomb was detonated on islands off Western Australia in Operation Hurricane, in October 1952.

The 1950s testing produced the Blue Danube bomb, Britain's first nuclear weapon, which was transported by RAF planes.

Britain later switched away from air-launched weapons, introducing the Polaris submarine-based system in 1968.

The final air-launched nuclear weapon was abandoned in 1998, according to the MoD, leaving Trident as the UK's deterrent.