A Canadian lawyer has launched a class-action lawsuit against Facebook, claiming the Internet site duped users into letting their private information be sold for profit.

Tony Merchant argues changes to Facebook's privacy settings over the past 18 months amount to a "classic bait-and-switch."

In court papers filed Friday in Winnipeg, he alleges the social networking website led users to believe that they were making their information more secure, but the changes actually opened people up to advertisers and data miners.

"People have put on their site very private information, very private pictures, might have put family secrets, might have put pictures of themselves partially dressed or naked, and in many instances people don't even remember what they've put on their Facebook some time ago," Merchant said Friday in a telephone interview from Regina.

"That then moves more or less into the public domain and it allows Facebook to send harvesters in looking for information.

"Facebook's purpose is to have data miners make their sale of your personal information more profitable."

Merchant said Facebook changed its default settings so that information is automatically shared with outside advertisers and websites.

Merchant said most people signed up for Facebook when the privacy settings were much more stringent, and that most users wouldn't have chosen to have their information shared had they been asked.

"The numbers of people would have been so minuscule who would have said, ‘Yes, mine my personal information for commercial purposes,'" he said.

The allegations have not been proven in court and the suit has not been certified as a class action.

At the end of May, Facebook founder Mark Zuckerberg announced changes that he said would solve some of the site's privacy issues.

But Merchant said the main concerns listed in the lawsuit remain.

So far, only a couple of hundred people have signed up to join his suit, but he expects many more will as word spreads.

"It's likely that we will have huge numbers of people contact us as they come to know about this case."