Germany's national consumer-protection agency may take legal measures against Facebook if it finds that the social network's new privacy controls do not meet German data-protection standards.

Carola Elbrecht, head of digital projects at the VZBV agency, welcomed the changes to privacy settings announced by Facebook late on Wednesday but expressed concern that users would still have to actively opt out of default settings making their data public.

This obligates the user, and that's a transgression of German law, Elbrecht told Reuters on Thursday.

We are currently examining the terms and condition of data storage and usage, and if it again does not comply with German data protection standards we will file for an injunction.

Germany has some of the toughest privacy laws in the world as a result of its experience with state surveillance systems put in place by the Nazis and the former East German Stasi secret police, and Germans have been vocal critics of Facebook.

According to independent information service Inside Facebook (www.insidefacebook.com), 7.7 million of Germany's 82 million people were active on Facebook in March. That compares with 113 million active U.S. users, of a population of 309 million.

Mark Zuckerberg, chief executive of the social network that has gathered 500 million users in six years, has bowed to mounting criticism by saying Facebook would give users more powerful tools to protect private information.

Elbrecht said: We certainly welcome anything that makes it easier and more transparent for the user to manage privacy settings -- that's a good step but it is not enough.

The VZBV, which represents 42 consumer groups in Germany, sent an official warning over the issue to Facebook and other social networks including News Corp's MySpace and Germany's Xing last year.

It said at the time it would go to court to prevent the practices it says are illegal if it was not satisfied with remedies proposed by the networks.

Under Germany's Telemedia Act, a website must get a user's permission before passing personal data to a third party for other purposes.

The Consumer Protection Ministry says this applies to foreign Internet companies operating in Germany as well.

Ilse Aigner, the consumer protection minister who is an avid user of social networks and a member of Facebook, in April threatened to quit Facebook in an open letter to Zuckerberg protesting against the company's use of personal data.

On Thursday, she welcomed Facebook's announcement but echoed Elbrecht's concerns over members having to opt out, not in.

I am skeptical whether this constitutes a complete change. We will have to wait and see what will truly change for members, Aigner said.

Caspar Carstens, an analyst with IT research firm Gartner, said: They took an important step in the right direction... but after going back and forth on privacy and data control, they face a credibility problem.

The Germans are never satisfied when it comes to data protection -- they are extreme when it comes to that.

(Additional reporting by Georgina Prodhan in London; Editing by Sharon Lindores)