New Facebook flap: Your face in some product's ad

NEW YORK (CNNMoney) -- A new Facebook policy that allows your picture to be used in a product or store's ad without your knowledge has privacy groups united in opposition.

Executives from six public interest groups on Wednesday signed a joint letter to the Federal Trade Commission asking that the agency act to stop Facebook's new privacy and data use policies.

"Facebook users who reasonably believed that their images and content would not be used for commercial purposes without their consent will now find their pictures showing up on the pages of their friends endorsing the products of Facebook's advertisers," said the letter. "Remarkably, their images could even be used by Facebook to endorse products that the user does not like or even use."

Facebook's new proposed policy was announced last week in the wake of a $20 million settlement of a class action suit about its privacy rules.

The new rules "while not incorporating all features that some of the objectors might prefer, has significant value and provides benefits that likely could not be obtained outside the context of a negotiated settlement," wrote Judge Richard Seeborg in his order approving the court settlement.

But the public interest groups argue that the settlement, and the changes that Facebook agreed to, do not go far enough, particularly when it comes to protecting the rights of minors who use the site.

"It requires 'Alice in Wonderland' logic to see this as anything but a major setback for the privacy rights of Facebook users," said the group's letter.

The posting on Facebook's site by Erin Egan, its Chief Privacy Officer, says the proposed changes in its rules were done to help its users understand how the social media site uses their information. But the comments from users at the bottom of the page announcing the changes were overwhelmingly negative.

"Send me ads, fine. Use my photos or posts in ads, I'm out of here," wrote Margo Kelly, one of the Facebook users posting a comment.

The groups whose executives signed the letter include the Electronic Privacy Information Center, the Center for Digital Democracy, the U.S. Public Interest Research Group and the Privacy Rights Clearinghouse.