Officials also seized assets from 15 bank, investment and advertising accounts, and executed residential search warrants in North Carolina, New Jersey, New York and Washington.
Immigration and Customs Enforcement officials worked with the US Attorney for the Southern District of New York and other government agencies. The investigation involved about 100 agents in 11 states and the Netherlands.
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Officials wouldn't say how many people were suspected of intellectual property theft, but said the penalties could include prison time.
The raids were the first actions in a new "Operation In Our Sites" initiative to combat internet counterfeiting and piracy.
The government only seized domain names for the sites in question, however, meaning the computers that run the sites could still be used under different names.
Acknowledging the slippery nature of online piracy, John Morton, the assistant secretary of Immigration and Customs Enforcement, said government agents would have to be persistent in chasing site operators.
"If a site reappears, so will we. If the criminals move overseas, we will follow," he said at a press conference on Wednesday on the studio lot of The Walt Disney Co.
"Take it from me, I don't think that we've stopped internet piracy in a day, but this is going to be a sustained effort."The domain names seized were: TVShack.net, PlanetMoviez.com, ThePirateCity.org, Movies-Links.TV, FilesPump.com, Now-Movies.com, ZML.com, NinjaVideo.net and NinjaThis.net. All the sites' domain names were registered in the US, although one was physically based in the Netherlands.
The sites had about 6.7 million visitors combined every month,and at least one had about a 10-fold increase in traffic from a year ago. They made money from advertising or donations.
Officials said the sites would be disabled. As of Wednesday afternoon, several of the sites checked by The Associated Press were still functioning. The ICE said it would take about a day before all the sites would show a banner saying the domain name had been seized.
Morton said there were hundreds of similar websites infringing on copyrights.
The conference was also attended by executives from Disney, Viacom Inc.'s Paramount Pictures, the Directors Guild of America, Motion Picture Association of America and the International Alliance of Theatrical Stage Employees, which covers behind-the-scenes workers in the movie industry.
US Attorney Preet Bharara said in a statement that money lost because of copyright infringement translated into lost jobs. The MPAA said film and television production supported 2.4 million American jobs and contributed $80 billion a year to the economy.
"That's why we took the actions that we did," Bharara said in a statement. "If your business model is movie piracy, your story will not have a happy ending."
