The piano used as the prop for the key flashback scene between Humphrey Bogart and Ingrid Bergman in the 1942 film Casa­blanca will go on sale next month.

Sotheby’s says the auction in New York should raise between €618,300 and €900,000 for the 58-key piano on which the film’s character Sam plays As Time Goes By for Rick and Ilsa.

“Here’s lookin’ at you, kid,” Bogart’s Rick tells Bergman’s Ilsa as the three drink champagne at La Belle Aurore in Paris, while loudspeakers outside announce the approach of the invading German army.

The December 14 sale will mark the 70th anniversary of Casa­blanca, ranked by the American Film Institute as the most romantic and quotable movie of all time.

The Warner Bros movie won three Oscars in 1943 for best picture, best writing (screenplay) and best director.

The piano was sold by Sotheby’s in 1988 to a Japanese collector.