One of the deactivation groups.

Facebook groups have launched a successful campaign to ban what they call "enemies" from the social network by reporting them to the site's administrators. Their main targets are human rights advocates, atheists, and those accused of being "anti-Islam" or simply "too liberal".

Lists of targets are compiled on Facebook itself, in groups like "Pesticide" and "The cleansing bureau". Hundreds of Facebook users are on the lists - especially if they're gay or women who refuse to wear the veil.

The group administrator asks members to alert the Facebook admin to the targets' accounts by signalling them as "fake profiles". And it's working. Hundreds of users, most of them from Tunisia but also elsewhere, have seen their accounts disappear.

That's because if a large enough number of people signal a profile, then it is deleted automatically, without human verification. Facebook, which is currently facing huge criticism for privacy issues, confirmed that the automatic system was in place, after an employee of the American company tested it.