The US Air Force ran an investigation into the matter until 1969 called Project Blue Book. It probed more than 12,500 UFO claims during the investigation.

The group, including former military officers from seven countries, claims that each one of them has seen a spaceship.

They insist that there is a need to conduct further probe into the apparent sightings of high-speed UFOs as it is a national security concern.

However, the Air Force does not see any point in resuming investigation as no substantial evidence regarding spaceships has emerged in the past four decades.

Democrat presidential candidate Dennis Kucinich and former Arizona Governor Fife Symington are among people who claim that they have seen UFOs. (ANI)