A leading privacy group has urged US regulators to investigate Google's new social networking service Buzz, one week after its launch.
The Electronic Privacy Information Centre (Epic) has made its complaint to the US Federal Trade Commission (FTC)
It says that Buzz - which is part of Google's Gmail service - is "deceptive" and breaks consumer protection law.
The search giant has twice made changes to the service to placate an outcry from users about privacy concerns.
Canadian officials are also looking at whether Buzz violates privacy laws.
"Google still hasn't gone far enough," Epic's consumer privacy counsel Kim Nguyen told BBC News.
"Twitter is a social networking site and people know what they are signing up for. With Gmail, users signed up for an e-mail service not a social networking service," said Ms Nguyen.
"Despite all the changes, they still do not give users a meaningful way to opt into it."
Buzz was automatically rolled out to Gmail's 176 million users.
The FTC has been asked to "require Google to provide Gmail users with opt-in consent to the Google Buzz service".
Since launching Google Buzz as part of Gmail last week, the search giant has faced a torrent of criticism regarding privacy.
The feature that attracted the biggest outcry was one which automatically gave users a ready-made circle of friends to follow based on the people they emailed the most.
Privacy advocates said that meant the list of contacts was open for all to see and could have had serious implications for journalists, businesses or even those conducting illicit affairs.
Engineers have now replaced the auto-follow feature with one that suggests who to follow but EPIC said that still leaves the "user with the burden to block those unwanted followers".
The organisation also wants the company barred from using Gmail address book contacts to make up social networking lists.
Google has apologised and said it acted quickly to address concerns including introducing a new option to disable the service.
"If it becomes clear that people don't think we've done enough, we'll make more changes," Todd Jackson, product manager for Google Buzz told BBC News.
He acknowledged that many of Gmail's "tens of millions" of users were "rightfully upset" and that the firm was "very, very sorry".
The botched launch of Buzz has led many to ponder how and why it happened.
In an interview with BBC News, Mr Jackson admitted that testing of the service had been inadequate and that it was not opened up to a big enough group of people to try out.
"We've been testing Buzz internally at Google for a while. Of course, getting feedback from 20,000 Googlers isn't quite the same as letting Gmail users play with Buzz in the wild."
The Consumer Watchdog, an advocacy group, said it was not surprised by this stumble.
"This case illustrates a lot about Google's corporate culture where a company is run by computer scientists whose operating method is don't ask for permission when you can always ask for forgiveness," said the organisation's John Simpson.
The move by EPIC to ask the FTC to investigate Buzz mirrors one it made in December against the world's biggest social networking platform Facebook.
Then, the privacy watchdog was not happy about changes the company made to its privacy settings.