Computer hacking group Anonymous has described a threat to “kill” Facebook over privacy concerns and the alleged use of user information by authoritarian regimes as a hoax.

A warning purported to be from the loosely-affiliated group of international hacktivists was issued through YouTube last month. It said it would take down the social networking site in November.

"Prepare for a day that will go down in history. November 5th, 2011," the video warned. "Your medium of communication you all so dearly adore will be destroyed."

However, on a Twitter account used by Anonymous, the group dismissed the threat as fake. “To press: medias of the world... Stop lying! #opfacebook is just another fake! We dont "kill" the messenger. That's not our style,” it said.

Anonymous has previously claimed responsibility for attacks on Rupert Murdoch's media empire and the website of the Syrian Defence Ministry.

"Facebook has been selling information to government agencies and giving clandestine access to information security firms so that they can spy on people from around the world," the video said, adding that some of those firms are working for authoritarian governments such Egypt and Syria.

"Facebook knows more about you than your family," it said. “You are not safe from them nor from any government. One day you will look back on this and realise what we have done here is right, you will thank the rulers of the internet, we are not harming you but saving you.”