A growing number of Facebook users have been reporting that ‘strangers’ have been mysteriously popping up on their friends list, and suspect that the problem could be linked to a new, unidentified virus or scam.

According to ReadWriteWeb, Facebook’s support forum has been inundated with complaints from users who claim that friend requests have been sent from their accounts to people they don’t know, or worse, people they had previously blocked.

One user, Monica Elenbaas, even saw her Facebook account blocked from sending any more friend requests after more than 100 were sent to random people on her behalf.

All evidence points to some kind of ‘worm’, although Facebook hasn’t yet made any statement other than to say the issue is being investigated.  Worms act differently from normal viruses that spread themselves through programs and files, instead using other means to hop from PC to PC.

Using Facebook as a means of spreading viruses is nothing new. Earlier this year, it was reported that the Steckt.Evl virus exploited Facebook’s instant messaging to spread itself around the web, before taking over computers, shutting down anti-virus programs and claiming the machine as part of its bot network.

For those who have already been affected by the new phenomenon, there’s little that can be done other than to get in contact with Facebook and let them know as soon as possible. No doubt changing your password is the obvious next step (just in case), but it’s possible that whoever has taken control of your account will have already done so. If that’s the case, Facebook has a procedure for people who want to reclaim their accounts here.

In addition, it’s a good idea to update your anti-virus software, delete any apps that have been installed recently (as well as those you never use), and finally be sure to let your friends know that your account has been compromised, just in case it starts spamming them with links or app requests that may contain viruses.