The NSA is using a top secret computer program that allows the 'widest-reaching' collection of online data about its citizens, The Guardian has revealed.
In documents leaked to the newspaper by whistleblower Edward Snowden, it is revealed a program called XKeyscore is sweeping up the emails, social media activity and browsing histories of millions of internet users.
Australian authorities are reported to be among a group of nations with access to the surveillance system alongside the US, UK, Canada and New Zealand.
Citing classified documents, the British daily reveals the NSA boasts the program is its "widest-reaching" system for sourcing web-based intelligence.
The documents appear to be a batch of slides from a confidential US intelligence training briefing which lays out the capabilities of the XKeyscore program.
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These capabilities are said to include the collection of "real-time" data of internet activity.
Citing an NSA report from 2007, The Guardian says the program enables 1-2 billion "call-events" to be recorded and stored each day.
The revelations come after former NSA contractor Edward Snowden leaked details in June about an agency program that gathers vast amounts of telephone data on nearly all Americans.
Mr Snowden is currently in Russia, holed-up in a Moscow airport awaiting the processing of a temporary asylum claim, charged with violating the United States Espianage Act.
The news of XKeyscore also comes as senior intelligence officials testified overnight before a Senate judiciary committee which is investigating the extent of government surveillance programs.
US lawmakers have also vowed to step up a campaign to reign-in the programs.
It comes after an amendment bill to strip the NSA of surveillance powers failed 205 votes to 217 in the House of Representatives last week.
The bill would have made illegal the collection of telephone data from Americans not associated with a terror investigation.
