The Electronic Privacy Information Centre (EPIC) has asked the US Federal Trade Commission to investigate Google's Buzz social networking tool.
EPIC said in the complaint that it is concerned about a number of features in Buzz, particularly the lack of control given to users.
"Last week, Google tried to transform its popular email service into an untested social networking service. As a consequence, Google displayed social networking lists based on a user's most frequent address book contacts," EPIC said in a statement.
Marc Rotenberg, executive director of EPIC, added that Google's move represented a "significant breach" of consumers' expectations of privacy.
"Google should not be allowed to push users' personal information into a social network they never requested," he said.
Google addressed some concerns last week, including handing over of control of contact information and settings to the individual user.
EPIC has said that it wants Google Buzz to be "fully opt out".
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