The United States National Security Agency collected almost 200 million mobile phone text messages a day from around the world that allowed it to extract contact networks and credit card data of users, according to the latest leaks from whistleblower Edward Snowden.
British spies have had access to some of the information extracted and stored from SMS messages by the NSA, the Guardian newspaper said in revelations based on files leaked by former NSA contractor Snowden.
The spy programme, codenamed Dishfire, collects "pretty much everything it can", rather than merely storing communications of existing surveillance targets, according to a joint investigation by the daily and Channel 4 News.
Dishfire analyses SMS messages to extract information including contacts from missed call alerts, location from roaming and travel alerts, financial information from bank alerts and payments and names from electronic business cards.
Through the vast database, which was in use as late as 2012, the NSA gained information on those who were not specifically targeted or under suspicion, the report said. The latest revelations state that the NSA's British counterpart, Government Communications Headquarters, had searched NSA's database for information regarding people in the UK.
The NSA, however, told the BBC that its programme only stored "lawfully collected SMS data". It added: "The implication that NSA's collection is arbitrary and unconstrained is false."
In a statement, the GCHQ said all of its work is carried out in "accordance with the strict legal and policy framework which ensures that our activities are authorised, necessary and proportionate and that there is rigorous oversight".
The latest revelations came a day before US President Barack Obama is to make a speech proposing curbs to NSA surveillance programmes exposed by Snowden. The changes will be based partly on a review of NSA activities by a White House panel.
Snowden has been charged with espionage in the US and is currently a fugitive in Russia, where he has been granted temporary asylum.
According to the report, another NSA programme called Prefer uses automated text messages like missed call alerts or texts sent with international roaming charges to extract information which the agency describes as "content-derived metadata", and explains that "such gems are not in current metadata stores and would enhance current analytics".
The NSA was also allegedly able to extract geolocation data from over 76,000 text messages a day, including from "requests by people for route info" and "setting up meetings".
Other travel information was obtained from itinerary texts sent by travel companies, even including cancellations and delays to travel plans. On Thursday, Obama briefed British Prime Minister David Cameron on the review of NSA surveillance activities, the White House said.
He discussed details of his speech during a phone call with Cameron, according to a statement from the premier's office.
During the discussion, the two leaders "welcomed the unique intelligence sharing relationship between their two countries", the statement said.