A hacker group known as Anonymous have said they will "kill" Facebook on November 5, in retaliation to what it calls a breach of privacy.

The most popular social media site in the world - Facebook has over 500 million registered users - has been selling information to government agencies and given access to information security firms to allow them to "spy on people", the hacker group alleged.

In a video posted on Youtube, the secret organisation called on "willing hacktivists" to join them in their battle against Facebook and privacy.

"Everything you do on Facebook stays on Facebook regardless of your 'privacy' settings, and deleting your account is impossible," it says.

Anonymous said it will take down the website on November 5.

"Your medium of communication you all so dearly adore will be destroyed," it said.

"If you are a willing hacktivist or a guy who just wants to protect the freedom of information then join the cause and kill Facebook for the sake of your own privacy."

Anonymous has been linked to a number of incidents, including bringing down the Playstation Network and hacking into the CIA.

They've also been linked to the hacking of the websites of infamous church Westboro Baptist.

The organisation is made up of hackers around the world who believe in the same goals set by the group.