Queen Elizabeth's underwear has sold for $18,000.

The pants were auctioned off on eBay by the estate of 'Baron' Joseph de Bicske Dobronyi, who died in 2010.

The listing claimed the British monarch had left the undergarments on a private plane when she visited Chile in 1968. The identity of the buyer is unknown.

The cream and lace-edged silk knickers are monogrammed with the royal crown and the letter 'E'.

The palace has refused to comment on the sale.

The auction listing said: "Since Buckingham Palace or the garment maker have not confirmed or denied the authenticity that this pair of underpants are from Her Majesty, Queen Elizabeth II, the estate cannot confirm its provenance and it is the buyer's responsibility to do that on their own before bidding.

"In either case this is an excellent example of a vintage undergarment of that era and very collectable."

Dobronyi is said to have been given the pants by the pilot of the private jet, who found them left on his plane.

Dobronyi was a Hungarian-born sculptor and jeweler. He made an emerald and diamond peacock brooch for Elizabeth's engagement to Prince Philip and a ring for her wedding present in 1947.