The Inspector General of Intelligence and Security Cheryl Gwyn found no evidence of unlawful spying.

A long running inquiry into whether the secretive Government Communications Security Bureau spied on Kiwis in the Pacific has revealed the mass collection of all communications channelled through certain satellites.

But there was no evidence of the spy agency acting unlawfully, the Inspector General of Intelligence and Security Cheryl Gwyn has found.

In a practice the GCSB labelled "full take", all communications data of certain types acquired from a particular satellite communications link was collected in pursuit of intelligence to protect New Zealand's interests in the Pacific.

CAMERON BURNELL/STUFF Nicky Hager released the documents that claimed NZ was spying on the Pacific region.

This potentially included the communications of New Zealanders.

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Gwyn's inquiry followed claims the GCSB carried out mass surveillance in the Pacific and allegations it had been unlawfully intercepting the communications of New Zealanders as part of its broad sweep.

The allegations date back to the Edward Snowden documents and the 2014 election campaign, when documents released by investigative journalist Nicky Hager showed the GCSB was engaged in wholesale spying on New Zealand's Pacific neighbours. Hager said the GCSB was passing the information directly to the United States National Security Agency (NSA).

Gwyn launched her inquiry after receiving complaints from individuals that their own information might have been accessed.

In the report released on Wednesday, Gwyn found that the GCSB did undertake signals intelligence gathering in relation to New Zealand's interests in the South Pacific during 2009-2015, including the collection of satellite communications.

CAMERON BURNELL/STUFF Government Communications Security Bureau director, Andrew Hampton, welcomed the report.

Significantly, Gwyn also found that GCSB was collecting and storing communications on a mass scale.

This effectively meant that everything channelled through certain satellites was indiscriminately hoovered up by the GCSB sweep.

This was one of Hager's central claims.

Gwyn said "full take" collection contrasted with collection that resulted in storage of "selected" data, which had been filtered by reference to selectors, like telephone numbers.

It was applied only to satellite communications links assessed by GCSB as likely to carry communications of intelligence value.

Unselected information collected and retained through "full take" could only be analysed by the application of structured queries and GCSB staff were required to monitor and review collected data at regular intervals to ensure the collection remained compliant and of foreign intelligence value, she said.

"There is no evidence that the GCSB deliberately targeted the private communications of any complainant for collection, or retained any data relating to any complainant. It is possible that some of the private communications of some complainants were collected as part of interception activity, either inadvertently (by mistake), or incidentally."

This inadvertent or incidental collection of their communications might have occurred either because it was caught up in the broader collection of communications, or because those individuals had communications with people or organisations who were a target.

"The likelihood that complainants' communications were collected inadvertently or incidentally ranges from zero to possible, considering variables of location, timing and the complainants' likely communication activity," Gwyn said.

But there was no evidence that GCSB retained any such data.

Gwyn also confirmed that some communications collected by GCSB in relation to the South Pacific were shared with its "Five Eyes" partner intelligence agencies. But it was unlikely that any data relating to any complainant's communications had been shared "given the targeted nature of such sharing and access and the safeguards against unauthorised access to the private communications of New Zealand nationals".

"I cannot determine conclusively, however, whether any data relating to any complainant might still be held in systems administered by partner agencies."

"The inquiry found no evidence that GCSB acted outside the relevant authorisations and statutory prohibitions to any significant extent. The exceptions were two inadvertent breaches that were detected and remedied."

At the time of the original allegations, former spy boss Sir Bruce Ferguson admitted mass surveillance was conducted on Pacific countries, but said information inadvertently collected on New Zealanders was not used.

Former prime minister John Key also said at the time the GCSB operated within the law.

"But we do have the GCSB and it is a foreign intelligence service and it does gather foreign intelligence that is in the best interests of New Zealand and protecting New Zealanders," Key said.

The Green Party was among those who lodged a complaint with Gwyn following the release of the documents, its former co-leader Russel Norman saying it was illegal for the GCSB to spy on New Zealand citizens and many Kiwis who lived or travelled to the Pacific might have had their data collected by the spy agency.

In a statement, GCSB director Andrew Hampton welcomed the finding that the agency did not deliberately target the communications of any of the complainants.

"I note that in the two instances where compliance issues arose, the Inspector-General found that they were both inadvertent. In each instance the issue was identified by GCSB staff, self-reported and corrected.

"In the report the Inspector-General states that although there is a possibility the GCSB collected communications of the complainants in the course of lawful activities, there is no evidence this occurred."

The Inspector-General also concluded that it was unlikely the GCSB shared the complainants' communications with its international partner agencies.

"This report helps to further emphasise that the GCSB is committed to acting lawfully and that the GCSB does not use its relationships with international partners to circumvent New Zealand law," Hampton said.

"As a signals intelligence agency the GCSB produces intelligence by collecting and analysing communications assessed as having an intelligence value in accordance with the priorities set by the Government.

"Our region's security has been an enduring topic of intelligence interest for successive governments.

"The nature of modern telecommunications means the GCSB may need to collect a broader set of communications in order to find and isolate the communications of greatest intelligence interest.

Hampton also pointed to a 2015 review of the GCSB's collection activities by Sir Michael Cullen and Dame Patsy Reddy.

That review was satisfied GCSB's activities did not amount to 'mass surveillance'."