The accounts of some Facebook users have been targeted with graphic images depicting pornography and acts of extreme violence, according to a growing number of reports coming from the United States last night.
The reports suggest the problem first began to be noticed last week but turned from a trickle into a flood over the weekend.
Some Irish users have also reported an increase in recent days in the level of pornographic content appearing on the news feeds when they log into the site.
One user from Dublin described the increased level of such material as “unbelievable”. She said it was “not so much on my page, but other eejits liking or commenting on it so it comes up on the news feed.”
Another said he had noticed “lots of porn and dating ads disguised as normal products until you click on them and then find strange apps on your Facebook page”.
The increased level of spam appearing on the social network has been linked to the online hacker group "Anonymous", which had previously made threats to target the site over concerns about the manner in which Facebook distributes and holds personal information and its plans to make money from users.
However, industry sources have cast doubt on whether the group is behind the increased level of spam as it does not fit with its modus operandi.
Spammers have apparently been taking advantage of the new photo-enhanced layout of the site - which means that when “friends” post comments on photographs the picture is automatically posted onto the news feeds of friends.
"It isn't presently clear precisely how the offending content has been spread - whether users are falling for a clickjacking scheme, are being tagged in content without their knowledge, have poorly chosen privacy settings, have been tricked into installing malicious code, or have fallen victim to another vulnerability inside Facebook itself," Sophos security expert Graham Cluley said on his blog.
"What's clear, however, is that mischief-makers are upsetting many Facebook users and making the social networking site far from a family-friendly place."
Facebook has confirmed that it is aware of the reports and is currently investigating the cuase of the problem.
