MoD staff recorded sightings of alien craft over Wallasey Town Hall and a saucer-shaped UFO hovering over Waterloo Bridge, it has been revealed.

Files detailing hundreds of sightings of UFOs in the skies have been opened to the public for the first time.

A form to record sightings is kept at police stations and airbases, but experts said information is checked for evidence of spying by other countries.