By Pete Harrison

LONDON (Reuters) - The government tried to cover up one of the country's most famous sightings of an Unidentified Flying Object (UFO), a parliamentary watchdog has ruled.

The "Rendlesham Files", which were finally published on the Internet on Sunday, contain eye witness accounts by U.S. Air Force officers at a military base close to Rendlesham Forest, near Ipswich in Suffolk, who saw a brilliantly lit object land in the forest in December 1980.

The incident is widely regarded as one of the most significant-ever UFO sightings -- the British equivalent of the 1947 incident in which a spacecraft supposedly crashed at Roswell, New Mexico, with aliens aboard.

Several people had complained to the parliamentary ombudsman, Ann Abraham, that the Ministry of Defence had refused to divulge full details of the Rendlesham witness accounts. Abraham ruled the ministry had "withheld three documents relating to reported sightings of unexplained aerial phenomena in 1980 -- the Rendlesham Forest UFO incident".

A ministry spokeswoman however said the files had not been deliberately withheld and had always been available to anyone who asked.

In late December 1980, U.S. officers investigating what they thought must be a crashed plane in the forest saw a triangular "strange glowing object" that sent farm animals into a frenzy.

"The object was described as being metallic in appearance and triangular in shape, approximately two to three metres across the base and approximately two metres high," reads a report in the file by Deputy Base Commander Lieutenant Colonel Charles Halt.

"It illuminated the entire forest with a white light," he added. "The object itself had a pulsing red light on top and a bank of blue lights underneath. The object was hovering, or on legs."

Sceptics say the witnesses were merely seeing the beam from a lighthouse on the nearby coast.

But the report adds that the next day three depressions seven feet (two metres) in diameter were found in the grass and that readings of beta and gamma radiation were ten times higher than normal. Disturbances were also noted on airforce radar at the time.

Later in the night, a second UFO was seen, described as a red sun-like light. "At one point it appeared to throw off glowing particles and then broke into five separate white objects," said the file.

A Ministry of Defence (MoD) memo in the file notes that: "No evidence was found of any threat to the defence of the United Kingdom. In the absence of any hard evidence, the MoD remains open minded."

Until last week, only around 20 members of the public had seen the file. The government said it would also be publishing other files on reported UFO sightings on www.mod.uk.

The Rendlesham File contains an MoD memo suggesting British requests for audio tapes made by the American officers at the time were brushed aside by the U.S. Later reports by UFO enthusiasts claimed that photographs and tapes were taken away by senior U.S. officers.

Copyright © 2002 Reuters Limited.