San Francisco, Nov 29 (IANS): To strengethen security for its over two billion users, Facebook may soon ask them to upload a photo that clearly shows their face to prove that they are not a bot.

According to Wired.com on Wednesday, the social media giant is using a new kind of captcha -- a type of challenge-response test used in computing to determine whether or not the user is human -- to verify whether a user is a real person or just a bot.

A screenshot of the identity test shared on Twitter read: "Please upload a photo of yourself that clearly shows your face. We'll check it and then permanently delete it from our servers."

Facebook later confirmed to Wired.com, saying the photo test was intended to "help us catch suspicious activity at various points of interaction on the site, including creating an account, sending Friend requests, setting up ads payments, and creating or editing ads".

A Facebook spokesperson was quoted as saying that the photo test is one of several methods, both automated and manual, used to detect suspicious activity.

The process is automated, including identifying suspicious activity and checking the photo. To determine if the account is authentic, Facebook looks at whether the photo is unique, the report said.

Further, users were locked out of their accounts while the photo was being verified.

A message said: "You Can't Log In Right Now. We'll get in touch with you after we've reviewed your photo. You'll now be logged out of Facebook as a security precaution."

Facebook users who suspect their account has been compromised can go to Facebook.com/hacked.