Margaret Thatcher is said to have ordered testing of a laser to be used in the Falklands War

A secret 'death ray' laser was developed during the Falklands War and ordered for testing by the then Prime Minister Margaret Thatcher, documents reveal.

Britain was said to have worked with America to develop the high powered lasers for use on the battlefield during the 1970s and 1980s.

The beam, nicknamed a 'death ray', had been developed quickly because of fears over the weapons possessed by the Soviets - but was never used.

But Lady Thatcher was said to be so impressed with the technology she ordered testing to take place during the Falklands War, the Daily Express reported.

Existence of the laser was revealed in the National Archives, in a letter - marked 'top secret' from the then Defence Secretary Michael Heseltine to Lady Thatcher in 1983 about the weapons owned by the Soviets and Britain's position.

It said: 'You may recall that we developed and deployed with great urgency a naval laser weapon, designed to dazzle low-flying Argentinian pilots attacking ships, to the Task Force in the South Atlantic.

'The weapon was not used in action and knowledge of it has been kept to a very restricted circle.'

The letter was revealed under the 30 year rule.

Sheffield academic Dr David Clarke found the letter in his search of the archives and said the 'naval laser weapon' referred to a device tested, but never used in anger, when troops were defending the Suez Canal in 1941.

Margaret Thatcher (pictured front, centre) visited HMS Hermes when it came back from the Falklands War

This device used powerful searchlights to dazzle pilots as they attacked Royal Navy ships.

In 1982, when the Falkland Islands was invaded, it was decided to use the same tactics to try and blind enemy pilots.

DEVELOPING LASER TECHNOLOGY In the 1980s Britain was said to be focused on developing medium power lasers directed against relatively softer targets such as eyes, optic and electro-optic sensors. These weapons was designed to target low flying aircraft by 'dazzling' pilots targeting ships. The 'death ray' was said to be unlikely to be unsuccessful in targeting ships but would work on humans. Britain's laser weapon research in the 1980s was covered by two programmes - known as Raker and Shingle. Advertisement

According to the correspondence from Mr Heseltine, Britain had been working with America on developing laser weapons since the 1970s.

Mr Heseltine also detailed fears in his letter to Lady Thatcher about the Soviets were developing a range of secret beam weapons.

However he said he was uncertain whether owning these weapons was useful.

In the letter he added: 'the Russians could be in a position to field such weapons by the mid-1980s (in fact, the Russians may already have deployed a laser weapon on the cruiser Kirov)'.