LONDON (Reuters) - Aliens from outer space have been visiting Britain for years and UFO sightings doubled after the film Close Encounters was released in 1977, according to secret files collating reports by members of the public.

New Mexico's float, depicting aliens on a spaceship, takes part in the 119th annual Rose Parade in Pasadena, California January 1, 2008. REUTERS/Mark Avery

The alien craft come in all shapes, sizes and colors but their occupants are uniformly green, the Ministry of Defence files show.

The archives (at www.nationalarchives.gov.uk/ufos) are the first batch of a four-year release programme of all the ministry’s UFO files from 1978 to the present day.

The ministry dismisses 90 percent of the reports as having mundane explanations and leave 10 percent with a question mark and the assurance they are no defence threat.

A 1983 report from a 78-year-old out fishing at midnight tells of following aliens in green overalls on to a spaceship and then being told to go away because he was too old and decrepit for their purposes.

Two years later, a typewritten letter to the ministry tells of an alien spaceship being shot down in the river Mersey in northern England by another spacecraft and of the author developing a warm friendship with an alien called Algar.

Just as Algar was about to reveal himself to the government he was killed by other aliens, the author of the letter writes. He was still in telepathic contact with an alien called Malcben from the planet Platone in the Milky Way, the author added.

Written at the top of the letter is the terse comment “No reply.”

The ministry has files on 11,000 sightings dating back to the 1950s. A few of the sightings made it into the national press and all were checked out in case they were Soviet aircraft probing Britain’s defences during the Cold War.

“Clearly some reports remain unexplained but we have found no evidence that these phenomena represent a threat to national security and therefore cannot justify devoting Defence resources to their investigation,” said an official letter in 1985.

WORKING PARTY

The term Unidentified Flying Object was coined in a U.S. Air Force report three years after the description ‘flying saucer’ was applied to a sighting in Washington State in June 1947.

In Britain, so worrying was the spate of reports that a secret Flying Saucer Working Party was formed to check them out.

Like the U.S. Air Force, it concluded flying saucers did not exist. But its final report in 1951 was still classified “secret/discreet” and given very limited circulation.

Not all sightings can be easily dismissed as the working of overwrought or intoxicated minds, or triggered by watching Steven Spielberg’s Close Encounters of the Third Kind.

Royal Air Force personnel, civil aviation pilots and air traffic controllers have also reported sightings and radar tracks that remain unexplained despite high-level investigation.

Among the most famous was the sighting on two occasions of unexplained bright lights landing near a U.S. airbase in Rendlesham Forest in southern England. Even the deputy commander of the base put his name to that 1980 report.