US National Security Agency collected almost 200m text messages a day

The US National Security Agency has collected almost 200 million text messages a day from across the globe, using them to extract data including a person's location, contact networks and credit card details, according to top-secret documents.

The untargeted collection and storage of SMS messages - including their contacts - is revealed in a joint investigation between the Guardian and the UK's Channel 4 News based on material provided by former NSA contractor Edward Snowden.

The NSA program, codenamed Dishfire, collects "pretty much everything it can", according to UK spy agency GCHQ documents, rather than merely storing the communications of existing surveillance targets.

The NSA has made extensive use of its vast text message database to extract information on people's travel plans, contact books, financial transactions and more, including of individuals who are under no suspicion of illegal activity.

An agency presentation from 2011 - subtitled "SMS Text Messages: A Goldmine to Exploit" - reveals the program collected an average of 194 million text messages a day in April of that year. In addition to storing the messages themselves, a further program known as "Prefer" conducted automated analysis on the untargeted communications.

The Prefer program uses automated text messages such as missed call alerts or texts sent with international roaming charges to extract the information, which the agency has described as "content-derived metadata", and explains that "such gems are not in current metadata stores and would enhance current analytics".