Facebook has revealed that it may use facial recognition software to identify people from their profile pictures. The new “feature” was revealed in a change to Facebook’s data use policy, sent out via email to users this week.

It suggested that facial recognition technology could be used to identify users from their profile pictures - for easier “tagging” in photos. In Facebook’s official notes on the change, the social network said, “We made a few updates to this section… to explain that we will use profile pictures to suggest tags of you in photos.”

Facebook already uses facial recognition in its “tagging” feature, but does not apply the technology to profile pictures  - the new change is designed, the network claims, to “facilitate” tagging.

The changes come at a time where Facebook’s privacy policies are under scrutiny due to the PRISM program, according to a Reuters report, and may raise concerns regarding the availability of such data to governments.

The “tag suggest” feature, which uses facial recognition software to identify users in uploaded photos, is already controversial. It’s not available in European countries due to concerns among regulators.

"Our goal is to facilitate tagging so that people know when there are photos of them on our service," Facebook Chief Privacy Officer Erin Egan said. Users can opt out of the service entirely, Egan pointed out.

Users on Facebook were concerned that the data might be used for adverts featuring people’s faces. “While I don't object to Facebook mining my data in order to decide which ads to serve to me, I strongly object to my photos or text content being used to create ads others will see on Facebook,” one commenter wrote.

"Can I say that we will never use facial recognition technology for any other purposes? Absolutely not," Egan said. “If we decided to use it in different ways we will continue to provide people transparency about that and we will continue to provide control."

“When you or a friend upload new photos, we use face recognition software - similar to that found in many photo editing tools - to match your new photos to other photos you're tagged in,” Facebook wrote when it announced Tag Suggest in 2011. “We group similar photos together and, whenever possible, suggest the name of the friend in the photos.”

Facebook has already come under fire from privacy groups such as Electronic Frontier Foundation this year for the scope of its Graph Search function, which allows users to search the site via people's interests, "Likes" and where they live, and can unearth posts that users may have believed were “hidden”.

ESET offers tips on how to stay private on Facebook in a detailed blog post here. Photo tagging and Tag Suggest can be disabled in Facebook’s main privacy menu.