Newly-declassified files allege that during World War II, then British Prime Minister Winston Churchill ordered a 50-year ban on the release of information about a suspected UFO encounter over coastal Britain.
The files were released Thursday from Britain's National Archives, and include a 1999 letter to the British Defense Ministry from an unnamed British physicist.
In the letter, the physicist said his grandfather - an RAF officer and Churchill bodyguard - witnessed the prime minister discussing the UFO incident and a ban on the information with wartime Supreme Allied Commander Dwight D. Eisenhower.
In the alleged close UFO encounter, a British spy plane returning from a mission over occupied Europe was approached and shadowed by a metallic UFO over coastal Britain. The crew is said to have taken photographs.
The defense ministry, responding to the 1999 inquiry, said it found no records of the encounter.
It also admitted that most UFO files prior to 1967 were destroyed after five years.
The documents purport to show Churchill ordering the records sealed to prevent mass panic and avoid a potential shattering of the public's belief in God.
Some information for this report was provided by AFP.