New documents leaked by former NSA contactor Edward Snowden suggest that spy agencies have beeen useing apps installed on smartphones across the globe to track people. The documents, published by The New York Times, the Guardian, and ProPublica, suggest that the mapping, gaming, and social networking apps available on smartphones can feed the National Security Agency and Britain's GCHQ spy agency personal data.

The publications outlined how data could be harvested from apps such as the Angry Birds game franchise or Google's popular mapping service. The apps on smartphones could disclose users' locations, age, gender and other personal information.

The agencies have traded methods for collecting location data from a user of Google Maps and for gathering address books, buddy lists, phone logs and geographic data embedded in photos when a user posts to the mobile versions of Facebook, Flickr, LinkedIn, Twitter and other services, the Times said.

The NSA said Monday it focused on "valid foreign intelligence targets."