A copy of a long-secret sex tape featuring Marilyn Monroe has been sold for $1.5 million (£750,000), according to the New York Post.

The 15 minute, 16mm film was reportedly shot in the 1950s and is said to show the blonde sex symbol engaged in oral sex with a unidentified man.

The footage was bought by a New York businessman who plans to keep it locked up, Keya Morgan, the memorabilia collector who discovered the film and brokered its sale, told the newspaper. The original film is reportedly still classified and held by the FBI.

The collector, who has seen the footage, said the man's face is never shown and Monroe does not look at the camera.

The copy was just sold last month. Declassified FBI documents from the 1960s mention a "French-type" film starring the late actress, who died in 1962 from an overdose of prescription drugs.