The world's most popular social network is once again facing some outside pressure, but this time it isn't apps sharing user information, rather a new facial-recognition photo tagging system.

Facebook stated yesterday on its official blog that its “Tag Suggestions” service is now once again available in most countries after being phased out earlier. When users add a new photo to their Facebook album this feature uses facial-recognition software to make suggestions on the identities of those in the photo.

Based on this information users can then tag those in the photo as the software suggests, without the permission of the person involved.

This move has been challenged by EU data-protection regulators, with a group of privacy watchdogs known as the 'Article 29 Data Protection Working Party', launching a study to test the new feature for possible privacy violations, Bloomberg reports.

According to Gerard Lommel, a member of the group, “Tags of people on pictures should only happen based on people's prior consent and it can't be activated by default.” He continued saying that such an automatic tagging system could hold lots of possible risks for users.

Concerned users can however disable the automatic tagging software if they don't want to be automatically suggested, with the company explaining on its blog how this is done.

Alongside the EU probe the UK and Ireland are also launching their own investigations, with Greg Jones, spokesman for the UK Information Commissioner’s Office saying, “We would expect Facebook to be upfront about how people's personal information is being used. The privacy issues that this new software might raise are obvious.”

Do you feel that Facebook's new auto tagging feature is overly invasive, even though only friends can tag one another in the first place, or is the EU simply blowing smoke for no reason?