Legendary Las Vegas illusionists Siegfried and Roy are fuming over a new tell-all book that accuses them of abusing their stage animals and indulging in group sex orgies.

The Secret Life of Siegfried and Roy has been written by former employees Jim Mydlach, Jimmy Lavery, Louis Mydlach and Henrietta Tiefenthaler.

The writers claim the duo harmed the white tigers they used in their act and frequently cruised beaches for gay sex.

A publishing insider tells American tabloid the National Enquirer, "The book says that they became great friends with (late pianist) Liberace, joining him on manhunting expeditions. They all had the same taste in sex partners, with a preference for young men and stagehands - and pornography.

"To achieve their special white tiger breeding, the duo looked the other way when the big cats were born with defects.

"Some of the tigers could barely walk because of pain, and the duo had surgeries performed on them.

Siegfried and Roy have called the book "a vicious smear job", claiming the authors are merely "disgruntled ex-employees".