NSA tracks 5 billion phone records every day, says Snowden documents

The US National Security Agency is collecting some five billion records a day on the location of mobile phones around the world, The Washington Post reported, citing documents from US intelligence leaker Edward Snowden.

The information is added to a gigantic database that shows the locations of "at least hundreds of millions of cell phones" worldwide, a stunning revelation that suggests the eavesdropping agency has created a mass surveillance tool, the report says.

Of the NSA surveillance programmes revealed to date, the geo-location project appears to represent the agency's largest in scale and scope. The NSA declined to comment on the report.

The data was scooped up by tapping into cables that link mobile phone networks - both American and foreign - across the globe, the Post said.

The location data was gathered with the help of 10 "sigads" or signal intelligence activity designators.

In an example given by the Post, one sigad called "stormbrew" collects data from two unnamed corporate firms which administer interception equipment. Then the "NSA asks nicely for tasking/updates," according to leaked documents.

Information from the phones of Americans travelling abroad also forms part of the database.