Image caption The Falklands conflict lasted from April to June 1982

The UK sent a laser weapon designed to "dazzle" Argentine pilots during the Falklands war, official documents show.

The device, despite being quickly developed, was never used during the 1982 conflict.

Defence Secretary Michael Heseltine wrote that knowledge of the device, designed to deal with low-flying aircraft, had been kept to a "very restricted level".

The Soviet Union was developing similar weapons at the time, he also noted.

The existence of the laser was disclosed in a letter marked "top secret" from 1983, now released by the National Archives under the "30-year rule" for such documents.

Mr Heseltine, who had recently become defence secretary, wrote: "We developed and deployed with very great urgency a naval laser weapon, designed to dazzle low-flying Argentine pilots attacking ships, to the Task Force in the South Atlantic.

"This weapon was not used in action and knowledge of it has been kept to a very restricted level."

His briefing on military capabilities also discussed laser weapon research and development programmes called Raker and Shingle, which were "proceeding at high priority".

Mr Heseltine claimed the Soviet Union would be able to fire field laser weapons by the mid-1980s but questioned the usefulness to the UK of having such devices.

The Falklands war lasted from April to June 1982, with the loss of 255 UK service personnel.