Australian intelligence authorities accessed private internet data gathered by the US National Security Agency even more than their British counterparts over a 12-month period, according to a previously unreported document released by Edward Snowden.

The document relates to the NSA's PRISM program, which takes chunks of users' online activity directly from companies like Google.

In the 12 months to May 2012, Australia's electronic spy agency, the ASD, then known as DSD, produced 310 reports based on PRISM. The UK produced 197.

Eric King from British activist group Privacy International found the document and told Lateline he was astonished.

"What we've now found out is that DSD, the Australian intelligence services, were using PRISM, they were having access directly to Google, Apple, Facebook and other big US companies which are right into heart of their customer's data and pulling that out," he said.

"The fact that [Australia] had a third more than even Britain used is astonishing to my mind."

The intelligence gathering is part of the Five Eyes network, that includes the US, UK, Canada, New Zealand and Australia.

The 2013 revelations from NSA contractor-turned-whistleblower Mr Snowden revealed the extent to which Five Eyes were harvesting private information from the internet.

Questions of mass surveillance

Questions are now being raised about whether or not Australians are under mass surveillance.

The ASD is prohibited from spying on the communications of Australians inside Australia, but all that changes when communications go offshore, for example with internet activity.

Just about every Google search and Facebook post touches a foreign server.

Research by Philip Dorling, now a visiting fellow at UNSW Canberra, as well as documents released by Snowden, revealed that the ASD runs taps on undersea fibre optic cables out of Sydney and Perth that carry international telephone and internet traffic.

Dr Dorling said the objective was to gather foreign data passing through Australia as well as any Australian data of specific interest to intelligence networks.

"In order to collect those bits and pieces that they want at a particular time, they basically take the whole lot and they do so at the shoreline so to speak, at the points where Australia is connected with global telecommunications, at the major exchanges in Perth and Sydney," he said.

Data scoop 'carefully targeted and focussed'

Former senior Defence Department official Allan Behm said this automatic scoop of personal data does not equal mass surveillance.

"ASD is very, very carefully targeted and focussed on what it does with collected information and I can't think of a circumstance where the data relating to an ordinary citizen going about their business would be of any interest to ASD whatsoever," he said.

But Dr Dorling said the fact this data is not deleted means the Government could decide to access it in the future.

"One of the interesting developments is the way in which intelligence community and law enforcement have started to move into what they describe as a pattern of life analysis, which is sifting through vast quantities of metadata to look for certain behavioural patterns and connections between people," he said.

"It's like having a global 24-hour-a-day, 365-day-a-year search warrant running on whole societies, including Australia."

The UK and US have been to forced to redraw surveillance laws after court cases and inquiries found some tactics were illegal.

But Australia continues to increase intelligence and law enforcement powers and there has not been a review of oversight mechanisms - something that disturbs Independent senator Nick Xenophon.

"Compared to the US and Britain the oversight we have of our intelligence agencies is not just anaemic but is almost on life support," he said.