By Sharon Gaudin

Just when it seemed that Facebook's privacy tumult was quieting down, more fuel was added to the fire this week.

Ten privacy advocate groups penned an open letter to Facebook CEO Mark Zuckerberg on Wednesday, asking him to make changes to the highly popular social networking site that will give users more control over their own data. The groups behind the letter include the Center for Democracy and Technology, the Electronic Frontier Foundation and the Center for Digital Democracy.

" 'Privacy' and 'social' go hand in hand: Users are much more social with people they know and choose, and much less social when their actions and beliefs and connections are disclosed without their control or consent," wrote the advocates. "We are committed to continuing this dialogue with you and ensuring that users can continue to be both social and private on Facebook . We hope you continue to engage with us and your users to make Facebook a trusted place for both public and private sharing."

Andrew Noyes, a Facebook spokesman, said the company is listening to privacy concerns and taking them seriously.

"We plan to continue to make control easy and effective for all the people who use our service and will continue to engage these groups and others in a constructive dialogue about these important issues," Noyes wrote in an e-mail to Computerworld. "Users rely on us to protect their data and enforce the privacy decisions they make on Facebook. We take this trust seriously and work aggressively to protect it."

The distribution of the letter comes after a bit of calm that followed months of user outrage that the social networking site was playing fast and loose with user information.

This spring, Facebook was hit with increasing criticism from privacy advocates and users after the Web site unveiled a bevy of tools that allowed user data to be easily shared with other Web sites. That move caused an uprising among users and even prompted a handful of U.S. senators to call on Facebook to amend its privacy policies .

To quell the uproar, Facebook last month unveiled new, simplified privacy controls . The new tools were aimed at making it faster and less complicated for users to tighten their privacy settings.

However, the advocacy groups that signed the open letter don't say that's not enough.