Eight UFO files have been made public so far but there are as many as 200 reports, which will become available over the next four years.
A National Archives spokesman explained that the UFO files are being released following requests made under the Freedom of Information Act, and due to a "proactive move by the Ministry of Defence for an open and transparent government".
Amongst the more official accounts is a United States Air Force report about a sighting of "unusual lights outside the back gate at RAF Woodbridge" in Suffolk in December 1980.
Witnesses have made drawings of the objects seen and reported as UFOs and these are included in the files, which have become available.
