Are extraterrestrials walking among us? A belief that aliens have visited Earth — and may even have stayed here — has long existed among conspiracy theorists and over-eager sci-fi fans. But those beliefs have not been echoed by the sort of people who have regular contact with Nasa — until now.

Space tycoon Robert Bigelow, whose company Bigelow Aerospace built expandable space habitats for the International Space Station (ISS), believes aliens have visited the planet — and may even be living here. The claim was made by Bigelow on the CBS show 60 Minutes.

The conversation focused on working with Nasa before it shifted to Bigelow's famous obsession with aliens, with the mogul investing millions into UFO research.

"Do you believe in aliens?" asked the interviewer, to which Bigelow categorically replied: "I'm absolutely convinced. That's all there is to it." He then took matters a step further by saying, "There has been and is an existing presence, an ET presence."

When the reporter asked if he wasworried that people might call him crazy for believing in such ideas, Bigelow replied: "I don't give a damn. I don't care."

Bigelow believes aliens are living right here on Earth iStock

Bigelow elaborated on how his interest in the subject was peaked after his grandparents had a close encounter with a UFO outside Las Vegas. Asked if he ever had any such encounters he admitted he had, but refused to divulge any specifics.

Bigelow Aerospace has in the past received referrals from the Federal Aviation Administration about reports of UFOs and other weird activity. The space mogul claims he has spent more money than any other American researching aliens and UFOs.