If you're a Facebook user that belongs to a network, it might be worth checking twice before posting content you may not want others to see, as U2 front man Bono recently found out to his cost.

The singer, who's well-known for his charity work, was snapped cavorting with two bikini-clad girls in St Tropez. Unfortunately for Bono, one of the girls - Andrea Feick - decided to post the pics on her Facebook profile. As a member of the New York network, the pics could be viewed by all of the network's million members, and presumably Mrs Bono. Whoops.

But its not just cheating spouses that could get caught out by Facebook's network privacy options. According to security firm Sophos, last year 75 percent of Facebook's London network were allowing their profiles to be viewed by other members of the network. Even more worrying was the fact that 54 percent were revealing their full date of birth - information that's vital to identity fraud.

"Facebook's privacy features are more sophisticated than some competing social-networking sites, but the fact that Facebook changes these without asking when you join a geographic network is a huge oversight. While in this instance the result is potentially embarrassing for Bono, other members of the site could easily find themselves the victim of identity theft," said Graham Cluley, senior technology consultant at Sophos.

The lesson to be learned: checking your Facebook privacy options could save more than just your marriage.

Bono and some teenagers in bikinis

Visit Broadband Advisor for the latest internet news, reviews, tips & tricks