A nude picture of Madonna is expected to sell for thousands at auction.

The photograph was taken for but never used in the singer's controversial 1992 book Sex—in which she posed for a series of X-rated photographs—and will go under the hammer at Bonhams' auction house in New York next month for an expected £5,000.

The snap, taken by photographer Steven Meisel, shows a topless 32-year-old Madonna reclining in bed while smoking a cigarette.

The sale will come as a blow to the 53-year-old pop superstar who has previously claimed she has never been able to put the erotic tome behind her.

She said: ''I hope that's not the only thing that I'm identified with—taking my clothes off. I have done other things. There's a lot more to Madonna than taking your clothes off.''

However, she has also defended the book as a part of her ''development'' as an artist.

Madonna previously said: ''When I published Sex, that was a subject that I was interested in exploring. And to me they're both reflections of who I was and who I am now. It's a, you know, kind of development of me.''