Britney Spears and her family have donated an autographed portrait of the pop star for charity, with a starting bid of $10,000 on auction site eBay.

The five-by-four-foot oil painting of the singer was given to the Los Angeles-based Promises Foundation, which provides behavioural health services to low-income women and their children.

"The Spears family gave us this painting out of their generosity," the organisation's director Lisa Rogg was quoted as saying by people.com. "It was their idea for the auction."

The eBay page shows several photos of Spears standing next to the artwork, as well as a letter of authenticity from her father Jamie.

The letter states: "I hereby verify that the portrait of my daughter, Britney, has been in our home since it was completed by the Daniel Maltman Studio."