The US' intelligence agency reportedly collected 200 million text messages a day worldwide as part of its wider mass surveillance programme.
According to classified documents revealed by whistleblower Edward Snowden, the National Security Agency used the messages to extract data including location, contact networks and credit card details.
The data collected by the NSA, under the programme codenamed 'Dishfire', had been used by its UK counterpart, the GCHQ, to search the metadata of "untargeted and unwarranted" communications belonging to people in the UK, the Guardian reports.
The documents indicated that Dishfire collected "pretty much everything it can", and not merely storing the communications of existing surveillance targets.
It was found that Dishfire collected an average of 194 million text messages a day in April 2011 and an additional programme, dubbed 'Prefer' conducted analysis on the untargeted communications by using missed call alerts or texts sent with international roaming charges to extract information.
Meanwhile, Vodafone, one of the world's largest mobile phone companies with operations in 25 countries including Britain, has expressed shock and surprise to the latest revelations.
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The company's privacy officer has said that Vodafone would be challenging the UK government over the alleged programme.
The latest revelations would intensify the heated global debate about individual privacy and national security, as US President Barack Obama prepares to formally announce some changes to the spy agency's activities of surveillance.