© UnknownArtist's impression
National Archives indicate 800 sightings in four-year period, while police and military staff are among those reported as UFO witnesses

Two terrified youths who ran into a Staffordshire police station were in no doubt they had seen a UFO land in a field near Chasetown after they experienced an intense heat when they were walking up Rugeley Road, Burntwood, at 11pm on 4 May 1995.

"Their skin turned a glowing red," said the Staffordshire police inspector's report. "They saw a darkish silver inverted saucer shaped object in a field, which was glowing red beneath. The object was about four houses high in the sky and about 40ft away from them. They then, reluctantly, went on to state that a voice, which came from a lemon-like head, which appeared beneath the machine, said: 'We want you, come with us'."

Neither was drunk or under the influence of illegal substances and the next day both provided the police with detailed written reports of what they had seen, but when the police visited the field a local farmer said he had been crop spraying there but had not seen anything unusual.

Officially documented reports of cases of attempted alien abduction may not feature strongly in daily Downing Street briefings but the release of the latest batch of the Ministry of Defence's UFO files reveals a hidden British obsession with flying saucers and such close encounters.

The 14 files released today by the National Archives include more than 800 sightings reported between 1993 and 1996, and contain more than 4,000 pages of material dating back to 1981.

This is the fourth batch of UFO files to be released since May last year and it indicates the MoD has been unwavering in its belief there is "no evidence whatsoever to suggest that intelligent life from outer space or alien spacecraft have landed on our planet".

But few of its correspondents appear willing to believe them, and for many UFO fiction quickly becomes UFO fact. This is borne out by the figures for UFO sightings, which peaked at 609 reports in 1996 - more than the three preceding years put together. A fact that may be explained by the popularity of Agents Scully and Mulder and the X-Files series broadcast on British TV that year.

The files do show, though, that not all the sightings and reports were without foundation. Bright lights seen across Devon and Cornwall, South Wales and Shropshire in the early hours of 31 March 1993 by 70 police and military witnesses were documented in more than 30 sightings reported to the MoD over a six-hour period. The reports said it was very big, shaped like a catamaran and was completely silent. The MoD's UFO desk, known as section (AS)2a, asked the RAF to replay its radar tapes but nothing unusual was detected.

The head of the UFO section told Sir Anthony Bagnall, the assistant chief of the air staff, that given the quality of the witnesses the sightings could not simply be written off: "It seems that an unidentified object of unknown origin was operating in the UK air defence region without being detected on radar; this would appear to be of considerable defence significance." There were detailed inquiries, particularly of the Americans, over whether they were testing any new "stealth" aircraft over Britain, but the MoD finally established what had been seen was a Russian rocket re-entering the earth's atmosphere after launching a Cosmos satellite.

Similarly, dozens of sightings, during 1993 and 1994, of a brightly illuminated oval object were reported over London. Inquiries established this was a Virgin airship advertising the launch of the Ford Mondeo but several correspondents refused to believe it.

The newly released files also throw light on an incident near an American airbase in Suffolk in 1980 known as Britain's "Roswell" - where it was claimed the US military had recovered an alien spacecraft in 1947. The file shows that Lord Hill-Norton, a former chief of the defence staff, told the then defence secretary, Michael Heseltine, that it was a "potential banana skin looming for the MoD". He said if the account of the sighting by the US deputy base commander at USAF Woodbridge had to be dismissed then it was evidence that a sizeable number of American military personnel at important bases in British territory were capable of "serious misperception, the consequences of which might be grave in military terms".

The so-called Rendlesham incident - after the forest near the base - remains Britain's best-known UFO sighting and confirms the general MoD view that "it is clear from the reports that we receive that there are many strange things to be seen in the sky".

Explanations can be found for most of them. Even the ufologists agree that in 99% of cases they will be aircraft lights, satellites in orbits or debris re-entering the atmosphere, high altitude kites, helium or weather balloons, searchlights or lasers.

But even the defence specialists admit there will always be some sightings that appear to defy explanation: "We remain open-minded about these," is the official position. Or as the president of Strange Phenomena Investigations put it: "There are still many wonders out there ... The search must go on."