A police helicopter crew gave chase to a UFO after it almost collided with their aircraft near a military base. The pilot was forced to bank sharply to avoid being hit by the mystery aircraft as the helicopter was returning to the Ministry of Defence base of St Athan, near Cardiff. The three crew, who described the UFO as 'flying saucer-shaped', then gave chase, getting as far as the North Devon coast before they ran low on fuel, it was reported. A spokesman for South Wales Police said: We can confirm the Air Support Unit sighted an unusual aircraft. This was reported to the relevant authorities for their investigation." It was reported that the aircraft closed in at great speed, aiming straight for the helicopter which swerved sharply. "They are convinced it was a UFO. It sounds far-fetched, but they know what they saw." The helicopter crew are said to have crossed the Bristol channel in pursuit of the UFO, but lost sight of it and had to turn back due to a fuel shortage. The sighting comes weeks after the most comprehensive Government files on UFO activity are opened to the public for the first time today and they disclose that even air traffic controllers and police officers have seen mysterious craft in the skies over Britain. The sightings [include] corroborated accounts from policemen and pilots of Unidentified Flying Objects hovering above towns and cities. All were recorded on official forms, held by air bases and police stations, and compiled by the Ministry of Defence between 1978 and 2002.