Social networking website Facebook has launched a new service called ‘Places’ which allows users to share their location with their friends.

The service, which has prompted security fears, also tells users which of their friends are at the same place or if they have ever “checked in” there before.

The new feature went live in Britain yesterday after its launch in the US last month. It is one of a new raft of social networking services that use the GPS function on many smartphones to work out exactly where a person is at any point, the Daily Mail reported.

The application, which works like popular location—based social networking site Foursquare, asks a user to click on the .

“Check In” button after logging into the website.

Once you click on the option, it displays a list of possible locations near where they are. When the users selects one of the options, it allows their friends to know about their location.

The service also lists nearby businesses and attractions, and Facebook will target the locations it lists to each Places user.

“Facebook is a place to share information with people you know,” said Facebook product manager Michael Sharon.

“We saw people were already using the site to tell people where they are, so the natural thing was to build a product to make this easier. This just formalises what people were doing anyway.”

Facebook, which has come under fire over its attitude towards privacy in the past, has installed a set of stringent new rules for its Places application.

Unlike other “always on” services, this application is optional and a user’s location is not stored unless they check in or accept a tag from a friend. Check—ins are defaulted to friends—only rather than everyone on Facebook.

In the “People Here Now” section users can see others who are checked in with you at that place. This section is visible for a limited amount of time and only to people who are checked in there, the website said.