The government took the threat of UFOs so seriously in the 1950s that UK intelligence chiefs met to discuss the issue, newly-released files show.
Ministers even went on to commission weekly reports on UFO sightings from a committee of intelligence experts.
The papers also include a wartime account claiming prime minister Winston Churchill ordered a UFO sighting be kept secret to prevent "mass panic".
Nick Pope, who used to investigate UFO sightings for the MoD, said: "The interesting thing is that most of the UFO files from that period have been destroyed.
