The Ministry of Defence has warned UK army, navy and RAF staff to disable Facebook Places, fearing that terrorists, particularly in Northern Ireland, could use the service to track targets.
The ministry believes Facebook Places, which was recently launched in the UK, could be a "one-stop shop targeting pack" and has grave concerns about its misuse.
"Social networks already provide an extensive open source intelligence gathering tool,” said the document.
“This application is almost creating a one-stop shop targeting pack, which could potentially be used to target military personnel, family and friends."
"The main concern relating to the use of the application is that it may inadvertently compromise the locality of a military user," the document said.
"Of significant note, users on operations in Northern Ireland are potentially putting themselves at risk by drawing attention to their exact whereabouts."
What is Facebook Places?
They ask their forces to deactivate the ‘People here now’ feature,’ which lets all Facebook users who are checked in at a location to see who else has also checked in.
Facebook Places allows users to "check in" to a place in order to let their contacts see where they are, in order to meet up with people or make new friends.
It also lets users check their friends in, though it requires the user’s permission to do it.
The MoD advised the military to block any such request and it also tells them how to stop third-party applications from getting their location.
On release of Facebook Places, Facebook said it was focused on maintaining user privacy.
Facebook has said it will bring the service to Ireland soon, but does not have a specific date at this stage.