Facebook has admitted it's been watching the web pages its members visit, even when they have logged out.
In its latest privacy blunder, the social networking site has been forced to confirm that it has been constantly tracking its 750 million users, even when they're using other sites.
It says the move was an inadvertent mistake.
Most would assume that Facebook stops monitoring them after they leave its site, but technology bloggers have discovered that's not so.
Data being regularly sent back to the social network's servers could be worth billions when creating 'targeted' advertising based on the sites users visit.
By Alexia Russell