A dress worn by Princess Diana, who died in a car accident in 1997, has been sold at auction in New York for around 600,000 dollars (around 550,000 euros). Auction house Sotheby's said four bidders competed for nearly five minutes for British designer Victor Gem's sleeveless, floor-length, purple gown. Among other things, Diana wore the dress for a photo shoot for the magazine "Vanity Fair" shortly before her death. The auction house did not initially say who bought it.