She guards her privacy jealously and will regard this as the ultimate betrayal.

Madonna's estranged brother has written a graphic tell-all memoir about his famous sister.

Christopher Ciccone no longer speaks to Madonna - a development which has been blamed on her marriage to Guy Ritchie.

Brother and sister: Madonna pictured with her brother in 1998, the pair are no longer close

Close friend Rupert Everett claimed that the Material Girl was forced to choose between the two because her film director husband is 'uncomfortable around queens'.

The unauthorised biography entitled Life With My Sister is due to be published next month and insiders have described the tome as 'graphic and interesting'.

Ciccone - a  Miami-based designer - was once extremely close to his sister and has worked with Madonna in the past, designing and directed  two of the stars biggest world tours,  'Girlie Show' tour in 1993 and Blonde Ambition in 1990.

However, the pair's relationship has become strained - particularly since Madonna's marriage to Guy Ritchie.

Although no details of the book's contents have been released the first print run is set to be 350,000 copies released on 15 July.

Publishers Simon & Schuster had been promoting an unnamed celebrity memoir for some months but did not reveal the subject until now.

Blamed: Madonna's marriage to Guy Ritchie is said to be the cause of the breakdown of her relationship with brother Christopher

The 47-year-old will not be short of material.

He was closely involved with Madonna's early career and worked as artistic director on his sibling's 1991 documentary, "Madonna: Truth or Dare,".

However, Madonna's spokeswoman Liz Rosenberg, said: ‘‘Madonna has not cooperated with any biography about herself.’’

The publishers are hoping the book will fly off the shelves.

The press release promised: 'Ciccone's extraordinary memoir is based on his life and 47 years of growing up with and working with his sister—the most famous woman in the world.'

Ciccone wrote the book with British journalist Wendy Leigh, who has also written the biographies of Liza Minelli, Arnold Schwarzenegger and Grace Kelly.

Close friend: Rupert Everett said that Madonna was forced to choose between her husband Guy Ritchie and brother Christopher because Guy was 'uncomfortable around queens'

Madonna's close friend Rupert Everett testified to the brother and sister's former close relationship in his 2006 autobiography, Red Carpets and Other Banana Skins.

He said: 'They had been inseparable in childhood and she had taken him with her to the material world, where he had provided a solid raft in the shark-infested waters...To know her at all you had to know him.'

But Madonna's relationship with Guy Ritchie meant she had to give up her brother, according to Everett.

He wrote: 'He and Guy were from different planets, and in a way the one's success relied on the other not being there...Guy was not particularly comfortable with queens.'

Madonna has also made her own revelations about her brother.

During an interview in the early nineties she accidentally revealed that he was gay without his permission after which they never worked together again.

"Ciccone's extraordinary memoir is based on his life and 47 years of growing up with and working with his sister - the most famous woman in the world,"  Publishers Simon & Schuster said this week.

It is due out next month, with a print run of 350,000

Ciccone has previously worked with Madonna and designed and directed her 'Girlie Show' tour in 1993.

He was also artistic director on her 1991 documentary 'Madonna: Truth or Dare'.

Madonna's spokeswoman said: "Madonna has not cooperated with any biography about herself."

The publisher had been promoting a celebrity memoir for July, asking bookstores to order copies without identifying the author or contents.