Motown singer Martha Reeves has claimed that a posting on internet auction site eBay has exposed her to identity theft.
Motown singer Martha Reeves has lodged a complaint
A contract signed in 1975 by the former lead singer of Martha And The Vandellas revealed her social security number.
The 63-year-old, whose hits included Dancin' In The Street, has complained to the Federal Trade Commission, and said she feels "completely exposed".
A spokesman for eBay said they cannot keep track of the site's 29 million postings, but do follow up complaints.
He added that if eBay employees spot a social security number on the site, they will remove it.
Reeves' lawyer Debra Trent said: "If this type of activity is allowed to go on, then celebrities will be at risk."
The president of the singer's fan club informed the singer that the contract for an appearance on a 1975 edition of Saturday Night Live was on the auction site - and included her social security number.
The information could be obtained simply by clicking on a photograph of the document.
It was the subject of a three-day auction on eBay and sold for $33.22 (£18.45) to a private buyer, who failed to list an address.
The link to the item has since been removed by the seller.