Players of popular cellphone games such as Angry Birds are having their information secretly harvested by government spies, leaked reports disclosed this week.

Britain's GCHQ officials collect data on the age, sex and location of app users. In some cases, they can record their political views and sexual orientation, claim reports based on leaked top-secret documents.

The British surveillance agency and its US counterpart, the National Security Agency, are said to use data to track suspected terrorists.

The dragnet takes in data from e-mails, phone calls and other electronic communications. The agencies' targeting of "leaky apps" was disclosed in documents leaked by Edward Snowden, the former NSA contractor.

Spies can also trawl details from Facebook, Flickr, Linked-In and Twitter.

The NSA has said that it does not put "everyday Americans" or "innocent foreign citizens" under surveillance.