NEW YORK (Reuters) - The piano from the Oscar-winning film "Casablanca" could fetch more than $1 million when it is sold at auction in New York next month on the 70th anniversary of the premiere of the classic movie, Sotheby's said on Tuesday.

The 58-key piano, on which actor and singer Dooley Wilson performed "As Time Goes By," has a pre-sale estimate of $800,000 to $1.2 million for the December 14 auction.

Wilson sang the song while playing the role of Sam in the 1942 film as Humphrey Bogart and Ingrid Bergman, the star-crossed lovers Rick and Isla, leaned on the piano in a flashback to their time in Paris.

"How can anything say 'I love you' better than the piano from Casablanca?" David Redden, vice chairman and director of the special projects department at Sotheby's, said in a statement announcing the sale.

The film, set in Morocco during World War Two, won three Academy Awards including best picture, best writing and best director for Michael Curtiz.

In 1988 when Sotheby's sold the piano to a Japanese collector it fetched $154,000, the highest price ever paid for a movie prop. Since then, interest in film props has grown, Sotheby's said.

Marilyn Monroe's white "subway dress" from the 1955 movie "The Seven Year Itch," sold for $4.6 million in Los Angeles last year, setting what Sotheby's says is a record price for an item of movie memorabilia.