In one, a military officer predicts embarassment if the public discovered a "absence of funds and greater priorities" had been stopping UFO investigations.
The 34 files incorporate sightings of lights over Glastonbury and a "flying saucer" in Nottinghamshire.
They can be downloaded free of charge for a thirty day period from the National Archives website.
National Archives consultant Dr David Clarke said it was about time the data was released.
"One of the most exciting files in the files is a piece from an intelligence officer, who fundamentally claims that regardless of thousands of reports that they've obtained since the Second Entire world War, they have by no means completed any study or invested any funds or time on the topic, and they say that folks just will not likely think that when they find out."
The inner memo from a DI55 [defence intelligence] wing commander dated 5 July 1995 says the media's portrayal of DI55 as a "defender of the Earth towards the alien menace" is "light years from the real truth."
The file shows the officer feared that if intelligence's interest in UFOs was to be uncovered it could lead to "disbelief and embarrassment since handful of men and women will imagine the real truth that lack of cash and greater priorities have prevented any review of the thousands of reports received."
A former Ministry of Defence UFO investigator stated the files reflected discussion over the significance of noted UFO sightings.
Nick Pope labored at the MoD in between 1991 and 1994.
He stated the files ended up really revealing: "The fascinating thing about these files is that they show that just as in modern society there's this large debate about UFOs - is it truly intriguing, are we currently being visited by aliens - or is it all just nonsense?
"We were acquiring the same debates in the Ministry of Defence. Some men and women thought it was a waste of time and money, other individuals thought it was of extreme defence importance ( via bbc.co.uk ).