Snowden leaks: NSA gathering 5 bn cellphone records a day

The US National Security Agency is gathering nearly five billion records a day on the location of cell phones around the world, a report in The Washington Post revealed today, even as UK authorities are grilling the editor of the UK's Guardian, which first broke the 'Snowden leaks' of the NSA's massive global surveillance programme.

The data is said to help the NSA track individuals and map those who they know to aid the agency's anti-terror work.

The records feed a vast database that stores information about the locations of hundreds of millions of devices, according to officials and the documents provided by former NSA contractor Edward Snowden, the report says.

The "dragnet surveillance" was condemned by digital rights groups who called for efforts to rein in the NSA's snooping.

The news comes as Microsoft plans to use more encryption to thwart NSA spying on it and its customers.

The huge database built up by the NSA keeps an eye on "hundreds of millions" of mobile phones, said the Post, adding that it let the agency map movements and relationships in ways that were "previously unimaginable".

The vast programme potentially surpasses any other NSA project in terms of its impact on privacy. The NSA has accumulated about 27 terabytes, according to leaked papers seen by the Post, that it was "outpacing" the NSA's ability to analyse the information effectively, the report says.

The analysis, via a computer system called Co-Traveler, was necessary as only 1 per cent of the data gathered was actually useful in its anti-terror work.

The vast majority of the information gathered is said to have come from taps installed on mobile phone networks and through use of basic location-information that network's log as people move around. Analysing this data helps the NSA work out which devices are regularly in close proximity, and by implication, exposes a potential connection between the owners of those handsets.

The American Civil Liberties Union said it was "staggering" that the NSA could mount such a vast location-logging system without any public debate. The "dragnet surveillance" broke US obligations that require it to respect the privacy of foreigners and Americans.