The United States National Security Agency (NSA) is collecting records from over five billion mobile phone calls around the world each day, according to new documents released by former NSA contractor Edward Snowden.
The data gathered is apparently used to track the whereabouts of hundreds of millions of individual phone users and map their relationships with other individuals.
Of all the NSA surveillance programmes that have been revealed since the first initial cache of documents was released by Snowden in June, this is potentially the largest in terms of scale and scope.
According to the files released by Snowden, the NSA collects the global data from 10 major signals intelligence activity designators, or "sigads". The Post reports that the agency's access to phone carriers' networks appears to be vast.
"Many shared databases, such as those used for roaming, are available in their complete form to any carrier who requires access to any part of it," Matt Blaze, an associate professor of computer and information science at the University of Pennsylvania, told the newspaper.
"This 'flat' trust model means that a surprisingly large number of entities have access to data about customers that they never actually do business with, and an intelligence agency — hostile or friendly — can get 'one-stop shopping' to an expansive range of subscriber data just by compromising a few carriers."
The NSA appears to focus its mobile phone data collection on "foreigners", however information is gathered on the foreign calls of US citizens ,as well as from the millions of Americans who travel abroad each year with their phones.
"As with other surveillance activities, the NSA claims that its cell phone location programme is targeted at foreigners, and Americans' information is collected only 'incidentally,'" said Elizabeth Goitein, a co-director of the Brennan Center's Liberty and National Security Program.
"But the scale of foreign surveillance has become so vast, the amount of information about Americans 'incidentally' captured may itself be approaching mass surveillance levels."