Matt Stone and Trey Parker are working on a musical about Scientology.

The 'South Park' and 'Book of Mormon' creators are planning to lampoon the controversial religion on the stage and its star follower Tom Cruise is horrified at the idea.

A source said: ''It's still being written but Tom is concerned he'll be the butt of the jokes.

''Tom caught wind of their plans and wasn't happy but then realised there isn't much he can do to stop it.''

Tom was recently paid tribute to by business tycoon James Packer, who claims the 'Mission Impossible' actor saved him from a deep depression and helped him join the Church of Scientology.

James said: ''When I was at my lowest, Tom Cruise reached out to me. He believed in me when other people didn't.

''I'd met him once or twice ... and he was in Australia and we got together. I think he could tell that I was in pain. He invited me to go to his house to go skiing with him at Christmas.

''And he never asked me for anything, in our entire life. He believed in me when other people didn't. I'm very grateful. I just think he's a very special person.''