A piano from the classic 1940s film Casablanca has been sold for $2.9M at an auction in New York, BBC News reported.

The instrument was sold along with over 30 items from the World War Two drama by Bonhams in Manhattan.

Pianist Sam, played by Dooley Wilson, sang As Time Goes By in the movie for actors Humphrey Bogart and Ingrid Bergman.

The piano was one of two used in the film and it had been owned by Los Angeles dentist Dr Gary Milan. He said the piano came with chewing gum under the keyboard but that the owner of the fingerprint embedded in it was unknown.

The piano featured prominently in the triple Oscar-winning film which was largely set in the Moroccan port city of Casablanca.

Humphrey Bogart uses the piano as a hiding place for illegal transit papers in a famous scene.

The letters of transit were also sold at auction for over $100,000.

Casablanca is ranked as the second greatest film of all time by the American Film Institute, just behind Citizen Kane.