The FBI dropped the curtain Wednesday on two movie piracy rings that specialized in sneaking digital camcorders into theaters and shooting hit films like "Ocean's Twelve" and "The Passion of the Christ," then duplicating and distributing millions of bootlegs worldwide.

Agents arrested 13 people in raids across the city, including some who were about to pirate the potential summer blockbuster "Superman Returns," which opened Wednesday.

Some of the DVD knockoffs included the FBI warning seen at the start of legitimate discs — "no small irony," Mark Mershon, head the bureau's New York office, said at a news conference.

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The counterfeiters had been operating since 1999. Industry officials believe they were responsible for nearly half of all the illicit recordings made in the United States.

Using computer file-sharing networks, the suspects distributed the counterfeit films to Pakistan, Singapore, Hong Kong, Malaysia and other countries, said Michael Robinson, an anti-piracy official for the Motion Picture Association of America.

The bootleggers "fueled a huge, huge underground economy," Robinson said.

Because counterfeiters sometimes bribe their way into advance screenings, their work can hit the black market before the movies are released in theaters — part of a broader scheme that the movie industry says robbed it of an estimated $18 billion (euro14 billion) in global revenue in 2005.

The MPAA contacted the FBI in 2003 after learning that a knockoff version of "The Matrix Reloaded" was circulating on the Internet.

The association's investigators had determined that the movie had been pirated during a special screening at a Manhattan theater. The FBI responded by launching an undercover operation targeting people known as cammers, who specialize in covertly filming movies in theaters.

Court papers said the FBI learned the cammers often used assistants, known as blockers, who "would sit in strategic positions surrounding the cammers so as to camouflage and conceal their filming activities" and "prevent people from blocking the view of the video camera."

The video shooters were paid several hundred dollars per film by manufacturers who would duplicate and package fake DVDs in counterfeit labels for distribution to street peddlers, the court papers said. The bootlegs sell for up to $19 (euro15) a piece.

The suspects were awaiting arraignment in federal court in Manhattan. Each could face up to five years in prison if convicted of conspiracy, copyright infringement and trafficking in counterfeit goods.