A series of never seen before nude Madonna photos taken in the 1970s are going up for auction.

The singer can be seen fully naked in many of the images, which were taken by Herman Kulkens in 1977.

They later came into the possession of Penthouse founder Bob Guccione, who died aged 79 in 2010.

His estate was bought out by Wall Street trader Jeremy Frommer last year and the Madonna photos came with it.

Speaking about the auction, Frommer told the Daily Mail: "We will also be selling 21 35mm slides, only six have ever been published...the craziest thing is that we still don't know who the mystery girl whose hair Madonna's playing with is."

Undated pictures of boxing champion Muhammad Ali as well as artwork by Guccione himself and a host of erotic images are also being sold off.

More details on the auction can be found here.

Despite being aged 55, Madonna is just as comfortable behind the camera now as she was back as a teenager. She recently posed for a series of racy Terry Richardson shots that were used in Harper's Bazaar magazine.