Facebook users could be asked to identify photos of their friends as part of a new secure way of logging in to the social network.

Facebook describes the security feature, which it has given the monkier of 'social authentication' as a type of 'captcha' and would be used to verify your identity if the social network has detected suspicious activity on your account, such as logging in from California in the morning and then from Australia a few hours later.

Captcha stands for 'Completely automated public turning test to tell computers and humans apart' and uses a box of jumbled letters that humans must decode to allow, for example, a registration to proceed.

"Instead of showing you a traditional captcha on Facebook, one of the ways we may help verify your identity is through social authentication," Facebook said in a blog.

"We will show you a few pictures of your friends and ask you to name the person in those photos. Hackers halfway across the world might know your password, but they don't know who your friends are."

However, Graham Cluely from security firm Sophos told the Metro, the move will create a stumbling block as "lots of people don't know their 'friends' that well."

Facebook said it will continue to test social authentication and gather feedback from users and the security community on how to make the process and other social features safe and useful.

In the same blog, Facebook announced it will let users connect to the social network using an HTTPS secure web connection, which offers extra assurance that they're connecting to the website that they intend to reach, while also encrypting the data sent between the PC and Facebook. The move is designed protect users from a widely publicised wireless networking attack called Firesheep .

See also: Mark Zuckerberg's Facebook page apparently hacked