Demi Lovato believes Simon Cowell’s chest hair is “getting dangerous”.

The 20-year-old star impressed as a judge on X Factor US last year alongside Simon, L.A. Reid and Britney Spears.

Throughout the show’s season Demi and Simon frequently engaged in fun-loving banter about the other’s idiosyncrasies.

But Demi thinks people should beware of Simon’s hairy man boobs as things are rapidly getting out of hand.

“Simon's shirt is always open,” she revealed on Friday’s episode of UK late night talk show Chatty Man.

“One more [button] and it will be [open to] his belly button. It is getting dangerous.”

Demi gets deeply absorbed in the patch of hair on Simon’s torso.

Apparently it can be a real diversion when she is concentrating on something else.

“I have never looked at his chest, his moob area. I am distracted by the bush on his chest,” the star explained.

Demi believes Simon takes good care of his chest hair.

She surmises that he primps it much like a hairstyle.

"I know the secret of his hair. He puts his head forward and then he blow-dries it. He does that every time before he goes on,” Demi laughed.

“He always gets the centre parting just right. I have never seen him with a comb trying to get it right. It is just how it falls.

“Maybe he uses the same extensions for his hair that he does for his chest.”