LONDON — Documents leaked by former NSA contractor Edward Snowden suggest that spy agencies have a powerful ally in Angry Birds and a host of other apps installed on smartphones across the globe.

The documents, published Monday by The New York Times, the Guardian, and ProPublica, suggest that the mapping, gaming and social networking apps that are a common feature of the world’s estimated 1 billion smartphones can feed America’s National Security Agency and Britain’s GCHQ with huge amounts of personal data, including location information and details such as political affiliation or sexual orientation.

The size and scope of the program aren’t publicly known, but the reports suggest that U.S. and British intelligence easily get routine access to data generated by apps such as the Angry Birds game franchise or the Google Maps navigation service.

The joint spying program “effectively means that anyone using Google Maps on a smartphone is working in support of a GCHQ system,” one 2008 document from the British eavesdropping agency is quoted as saying. Another document — a hand-drawn picture of a smirking fairy conjuring up a tottering pile of papers over a table marked “LEAVE TRAFFIC HERE” —