London, July 28 - Pop star Madonna's erotic private phone calls and answering machine messages meant for her former lover in the 90s are set to be auctioned and are expected to fetch $40,000.

Contactmusic.com reports that Madonna even faxed messages to her ex-boyfriend Jim Albright and left steamy messages on his voice mail. These letters and calls will now be auctioned off.

The messages are on two cassette tapes. The sale is organised by Gotta Have It auction house and will be held online. It will be held Aug 5.