Facebook suffered yet another attack on its privacy practices this week when a number of privacy watchdogs sent letters to Congress and the Federal Trade Commission asking for an investigation.

Facebook suffered another attack on its privacy practices this week when a number of privacy watchdogs sent letters to Congress and the Federal Trade Commission asking for an investigation.

The groups said they have serious concerns over Facebook's new privacy policy , and the subject of other complaints, including at the end of April.

The complaint with the FTC was accompanied by a letter to Congress pleading for it to push the FTC into an investigation of the company.

"Facebook continues to manipulate the privacy settings of users and its own privacy policy so that it can take personal information provided by users for a limited purpose and make it widely available for commercial purposes," the letter to Congress read. "The company has done this repeatedly and users are becoming increasingly angry and frustrated."

Specifically, the groups objected to Facebook's new requirement that users designate personal information as publicly linkable Links, Pages, or Connections. Even opting out of those settings - a confusing and laborious process, the groups said - still revealed that information on friend pages and on Facebook partners that the site connects to, such as Yelp. The groups also wrote that clicking a "Like" button on a third-party Web site allows that site access to a user's personal information, something that is not fully disclosed to the user.

Interestingly, the complaint also serves as a detailed step-by-step tutorial for opting out of the private information the groups said they're concerned about.

The letter to Congress openly worried that the FTC either lacked the power or the motivation to pursue questions of privacy at Facebook and other companies, and urged Congress to more closely monitor the agency, as per its oversight obligations.

The complaint was filed by fifteen groups, including: The Electronic Privacy Information Center, the Bill of Rights Defense Committee, the Center for Digital Democracy, the Center for Financial Privacy and Human Rights, the Center for Media and Democracy, the Consumer Federation of America, the Consumer Task Force for Automotive Issues, Consumer Watchdog, the Foolproof Initiative, Patient Privacy Rights, Privacy Activism, Privacy Journal, the Privacy Rights Clearing House, the United States Bill of Rights Foundation, and U.S. PIRG.

Ten privacy groups also filed a similar privacy complaint against Facebook in Dec. 2009 [corrected].