New York (AFP) - The painted upright piano that adorned Rick's Cafe in the classic movie Casablanca fetched US$3.4 million (S$4.25 million) at auction Monday after a frenzied sale in New York.

The orange piano - on which Sam (Dooley Wilson) famously plays As Time Goes By at the request of his one-time love Ilsa (Ingrid Bergman) - was among 200 items from Hollywood's golden age that went under the hammer at Bonham's in New York.

The piano featured prominently in the Oscar-winning 1942 romantic drama, with leading man Humphrey Bogart using it as a hiding place for the letters of transit that ultimately secure his former lover's safe passage to the United States.

Dresses worn by Grace Kelly, Marilyn Monroe, Judy Garland and Rita Hayworth were also auctioned, as well as a jacket worn by Clark Gable in Gone With The Wind (1939). The Lion costume worn by Bert Lahr in The Wizard Of Oz (1939) was also put up for sale.

Auctioneers had declined to estimate the Casablanca piano's likely price, saying only that they expected it to fetch "the low- to mid-seven figures." Bidding opened at US$1.6 million and escalated rapidly before closing three minutes later at US$3.4 million including taxes.

The piano was specially adapted to allow Bogart's character to perform his sleight of hand with the transit papers, hiding them in plain sight of the clientele at Rick's.

The writers decided that the papers should be stashed in the top of the piano, but had to alter its lid to make it work on camera.

"The only way this works, however, is if the lid opens from the rear, otherwise Rick would have to reach over Sam's shoulder to hide the papers, a hardly subtle move," the auction house said.

"The solution to this staging problem was to have the prop department completely remove the top of the piano, leaving the piece secured by a hook and eye only."

Most likely made in 1927, the piano also has only 58 keys, 30 fewer than a classic piano. It had been owned by a dentist in Los Angeles since the 1980s.

Bonham's said the painted Moroccan designs were restored about three decades ago under the direction of Warner Bros.

The piano was offered for sale with a signed photograph of actor Dooley Wilson and a copy of Casablanca, and even came with a wad of petrified chewing gum found stuck beneath the keyboard. A faint outline of a fingerprint could be seen on the gum, but its owner was unknown.