Warner Bros. is investigating how the first 36 minutes of the newest "Harry Potter" film came to be posted on the internet late Monday night, four days ahead of the movie's worldwide theatrical debut, The Wall Street Journal reported in its Thursday edition.

A spokesman for the studio, a unit of Time Warner Inc., declined to say whether it had yet figured out the source of the leak, but said an investigation was underway. The spokesman said the early release wasn't a promotional gambit.

The watermarked footage was made available for download on BitTorrent file-sharing sites such as IsoHunt.com and thePirateBay.org. Copies were still available Wednesday, though Warner Bros. said it was working to remove the illegal copies.

As part of its distribution process, Warner Bros. sends out watermarked prints of the film to theaters around the world.

It's unclear if the leak will affect the performance of the film, the seventh installment in the "Potter" franchise. The film series is the most lucrative in history, having surpassed both the "James Bond" and "Star Wars" series in 2007.

The previous six "Potter" movies have taken in about $5.4 billion world-wide; Warner counts more than $1 billion in profit from them. The eighth and final "Potter" installment will hit theaters next summer and will be in 3D.

When an early version of Twentieth Century Fox's "X-Men Origins: Wolverine" leaked about a month before the film's May 1 release last year, it may have diminished the audience's appetite for the film.

"Wolverine" went on to take in more than $373 million world-wide for Fox. That's considerably less than 2006's "X-Men: The Last Stand," which took in more than $450 million, or 2003's "X2: X-Men United," which took in more than $400 million. Fox is owned by News Corp., also the parent of The Wall Street Journal, FOX Business Network, and NewsCore.

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