The 'Angels' hitmaker ' who lives in Los Angeles with wife Ayda Field - is a keen follower of paranormal activity and says his most shocking close encounter came when he was relaxing at a luxury hotel in California.
He recalled: 'There's been a few times I've seen something but the main one came when I was staying at the Beverly Hills Hotel when I was completely sober.
't was half 10 in the evening. I was on sun lounger on the patio next to a young lady who shall remain nameless because she's married. There were palm trees about 40ft away from us down the patio then all of a sudden the sky blacked out, there was no stars anymore but about 200ft up there was a square object that hovered for a while then moved on.'
Despite his conviction in what he saw, Robbie finds it amazing that people often cast doubt on his alien observations.
He added: 'That happened and you tell a lot of people and they go 'You're a nutter.' I was with the young lady who also saw it, but I've seen a few other things I can't explain.
'The puzzling thing for me is . I don't know if they're paranormal or a trick of the mind or whatever, who cares, but I'm interested in it and I find it weird that people say, 'No you didn't,' or, 'You're mental,' because I really did, I wasn't drunk or high or anything.
'The fact of the matter is it might have been an American secret plane or something, who knows? But I hope it was an alien.'