Ontario police seized 75,000 illegal copies of some of this summer's biggest blockbusters and rounded up at least a dozen suspects Sunday, capping off an eight-month sting operation that investigators say ended in one of the largest anti-piracy busts in Canadian history.

On Monday, officers from the Peel region said they may now charge up to 21 people for allegedly running the illegal DVD market, which hawked still-in-theatre titles such as the Michael Moore documentary Sicko and The Simpsons Movie for as little as $4 a disc.

The pirated films were sold by merchants operating out of a Mississauga flea market at Mavis Rd., as well as at least one other Mississauga market, police said.

"As far as the sheer numbers involved, with the number of entries and the amount of arrests, the volume of DVDs seized, the money, the lab equipment — it's pretty significant," Peel police Det. John Mans said of the bust.

CBC News learned about the piracy investigation and checked in on the black market operation a few weeks ago using hidden cameras. The undercover report found that the operation was so efficient that $4 copies of The Simpsons Movie had already appeared on store shelves just 14 hours after the film began premiering in Canadian movie theatres.

Reproducing $21 million in movies a year

Investigators said business was brisk at the illegal markets. Even as officers were slapping cuffs on suspects, loyal customers were asking when the stores would reopen, the lead investigator told CBC News.

"You've got all walks of life coming in there — old, young, men in wheelchairs coming up asking for a television series they want and giving their names and phone numbers," Det. Mans said. "It's amazing. People are just completely oblivious to the fact that it's entirely illegal."

In all, Peel investigators believe the piracy ring was reproducing $21 million in Hollywood movies a year.

Canada, in particular, is a hotbed for movie piracy, with the Canadian Motion Picture Distributors Association saying that up to 25 per cent of all pirated films originate from illegal recordings done in Canadian theatres.

In an act of protest against what it feels are Canada's lax anti-piracy laws, Warner Bros. recently threatened to delay its movie premieres and stop handing out promotional copies in Canada.