Oprah tells staff to call her Mary

Talkshow star Oprah Winfrey's father is not actually her biological father, no one is allowed cellphones in her presence, and her staff call her Mary.

And the most powerful woman on television may not have been sexually abused as a child, as has been widely claimed, according to a new, unauthorised biography released in New Zealand today.

Oprah: A biography, written by Kitty Kelley, will cost $39.99 and is expected to be one of this year's best sellers.

About half a million books are being released worldwide.

The book reveals that Winfrey does not know the identity of her biological father and has been begging family members for years to tell her.

Kelley, who is known for her revealing biographies on the likes of Frank Sinatra and Liz Taylor, spoke to Winfrey's 81-year-old aunt who revealed who Winfrey's real father was, but who Kelley has chosen not to name in the book.

Other revelations include claims that Winfrey's staff refer to her as "Mary" at all times, to prevent outsiders from understanding who they are talking about.

Another is the total ban of mobile phones in her presence - to prevent secret photographs - and when phoning Winfrey's mother, Bernita Lee, callers are asked to key in a personal code or the call cannot be connected.

Other potentially damaging revelations - as told by family members - is that the talkshow host, who is widely believed to have been sexually abused as a child, was in fact not.

The biography is the first of its kind on the world's most dominant woman on television and her power and influence has already been evident in the US, with Kelley being blacklisted by many talkshow hosts to speak about the book.