Cee Lo Green worries about his Gnarls Barkley partner.

The US singer - whose new solo song 'Forget You' has been a huge worldwide hit and spent two weeks at the top of the UK charts - admitted he worries about the dark side of the other half of his band, Danger Mouse's, character.

He said: "I don't really have an in-depth opinion about anything Danger does outside Gnarls but I feel the mood of things he's done and it concerns me about a real part of him that I do know.

"I know he's not pretending - that's truly his mood and it's very dark and melancholy and bitter and sad and detached and Disturbed."

The upbeat soul singer explained although he knows his friend - who is currently said to be producing the U2's latest album - has a lighter side but, working with him takes its toll on his own state of mind.

He said: "I also know a lighter side of him that he will share with me but he won't share with the world. Danger Mouse is Danger Mouse 24 hours a day - I couldn't bear the thought of people being so utterly convinced I'm Gnarls Barkley 24 hours a day. I needed a break from it."