The space travellers' accounts of strange space sightings were examined under laboratory conditions.

All four astronauts taking part passed the test, carried out using the latest technology.

Experts say the results prove they were "completely convinced" signs of alien life they claimed to have witnessed during historic missions were genuine.

Aldrin, Al Worden, Edgar Mitchell and Gordon Cooper all took part in the study.

The Institute of BioAcoustic Biology in Albany, Ohio, carried out complex computer analyses of the astronauts' voice patterns as they told of their close encounters.

Although the technology is still top-secret, these studies are claimed to be more reliable than current lie detector tests and could soon replace those used by the FBI and police.

One of the first tested was Apollo 11 pilot Buzz Aldrin, now 88 – the second human to set foot on the lunar surface in 1969.

Aldrin has always maintained he spotted a UFO on the way to the moon, saying: "There was something out there that was close enough to be observed, sort of L-shaped."

BioAcoustic's Sharry Edwards said tests reveal Aldrin is sure he saw the UFO even though his logical mind "cannot explain it".

Apollo 15 pilot Al Worden, 86, stunned Good Morning Britain viewers when he claimed to have seen extra-terrestrials.