Facebook has incurred the wrath of privacy groups because of proposed policy changes it announced last week.

The executive directors of the Electronic Privacy Information Center and the Center for Digital Democracy penned a letter (pdf) to Facebook CEO Mark Zuckerberg urging him to withdraw changes that they say would impact the privacy of the social network's 1 billion users and break its previous settlement agreement with the Federal Trade Commission.

The battle began when Facebook announced a proposal to overhaul its system last week, saying that it had outgrown its old model. The two groups say there are three key components to the proposed changes that are troublesome.

The first proposed change involves the social network's wish to abolish users right to vote on changes in site governance. Currently, if a proposed change gets 7,000 "substantive comments," all Facebook users can vote on the change and the vote will be binding if more than 30 percent of all active registered users agree to the change.

Another problem the consumer groups have is with the proposed change to the social network's Data Use Policy. This policy explains how the site collects and uses data with its affiliates and changes to it could affect Instagram users' privacy. Finally, the third troubling change, according to the consumer groups, are new tools for managing Facebook Messages, which replace the "Who can send you Facebook messages" setting with new filters for managing incoming messages.

"Because these proposed changes raise privacy risks for users, may be contrary to law, and violate your previous commitments to users about site governance, we urge you to withdraw the proposed changes," the organizations wrote in their letter to Zuckerberg.

Facebook launched its current site governance model, which gave users the right to vote on site governance issues, in 2009. That same year, it also came under fire from the FTC when several watchdogs filed a complaint charging the social network with exposing information users had previously set to private. The social network settled the issue with the FTC last year and signed an agreement in August.

Under terms of the settlement, Facebook has agreed to provide users with "clear and prominent notice" anytime their information is shared. But before that can happen, Facebook must obtain its users' "express consent" before sharing any information that exists outside the auspices of its privacy settings. In addition, the agency will force Facebook to maintain a "comprehensive privacy program," and subject its service to biennial privacy audits.

Both the Electronic Privacy Information Center and the Center for Digital Democracy said Facebook's new proposed changes break the terms of this settlement.

"The settlement prohibits Facebook from misrepresenting the extent to which it maintains the privacy or security of covered information," the organizations wrote in the letter. "Additionally, prior to any sharing of users' personal information with a third party, Facebook must make a clear and prominent disclosure and obtain the affirmative express consent of its users."

A copy of the letter was sent to the FTC and, according to the Los Angeles Times, the organizations will file a complaint with the government if they don't hear back from the social network. When contacted by CNET, Facebook declined to comment on the issue.