The claim by Edward Snowden that New Zealanders’ internet traffic is accessible through a NSA intelligence database “may well be right”, the country’s prime minister, John Key, has acknowledged.

Key refused on Wednesday to rule out that New Zealanders’ metadata was being intercepted by American intelligence, telling local media: “I don’t run the NSA any more than I run any other foreign intelligence agency or any other country”.



But he denied that agents from the country’s spy agency, the Government Communications Security Bureau (GCSB), were helping feed mass Kiwi metadata into the vast and controversial database known as XKeyscore.



Documents obtained by Snowden, the NSA whistleblower, published on Monday, revealed that the New Zealand government worked throughout 2012 and 2013 to implement a domestic mass surveillance program.



Codenamed Speargun, the program involved installing “cable access” equipment to monitor the Southern Cross cable, which carries most of New Zealand’s internet traffic to the world.



Snowden wrote an accompanying post to the documents warning Kiwis that he had been able to search their intercepted metadata while an analyst with the NSA. “If you live in New Zealand, you are being watched,” he said.

Key has acknowledged the existence of Speargun, but said he raised concerns it was targeted too broadly and put a stop to its rollout in March 2013.

The prime minister told Radio New Zealand on Wednesday that New Zealand intelligence did supply “some information” on individual “persons of interest” to the Five Eyes intelligence network database, but that it was not obtained by “mass, whole surveillance”.

“You could not gather information about New Zealanders without a warrant,” Key said.

Five Eyes is an intelligence-sharing alliance between the security agencies of the Australian, Canadian, US and UK and New Zealand governments.

Asked about Snowden’s claim that Kiwi metadata was accessible through XKeyscore, Key said: “I think the point he was making was, in that shared database, he said ‘I regularly came across information about New Zealanders’ ... That may well be right.”

But he denied that New Zealand intelligence was “contributing that metadata”. “We don’t have the capability for mass surveillance,” he said.

However, he added, “we don’t control what other agencies and other people collect, there might be a variety of reasons for that”.

The country’s intelligence watchdog, Cheryl Gwyn, who is conducting a review into the lawfulness of the GCSB’s work, issued a statement on Wednesday claiming she had found no evidence of mass spying by New Zealand spies.

“I can advise that I have not identified any indiscriminate interception of New Zealanders’ data in my work to date,” she said. “I will continue to monitor these issues.”

Government surveillance has emerged as the surprise issue of the final week of New Zealand’s general election campaign, dominating local media ahead of Saturday’s poll.

On Monday evening, internet entrepreneur Kim Dotcom, a New Zealand resident, held an event at Auckland Town Hall where Snowden, journalist Glenn Greenwald, and WikiLeaks founder Julian Assange expanded on the Speargun revelations.

The event doubled as a campaign rally for Dotcom’s new Internet party, which hopes to win enough seats on Saturday to claim the balance of power in New Zealand’s parliament. Dotcom, who was illegally spied on by the GCSB in 2011 and 2012, has promised to remove New Zealand from the Five Eyes’ alliance if his party can win enough seats.

Greenwald has told local media that more “significant” revelations about New Zealand’s foreign intelligence agency will be disclosed in the next week few weeks, likely before the country’s bid for a temporary seat on the UN security council comes to a vote in October.

“I don’t want to give you the reporting before it’s ready, Greenwald said. “But what I feel comfortable saying is part of the reporting will identify the other nations on which the GCSB spies, either for its own purposes or at the behest of the United States.

“And that list includes adversary countries that most New Zealanders will probably expect and want the GCSB to be spying on. But then it also includes countries which I think will be very surprising, including western democracies or neighbouring countries or countries that are deemed allies of New Zealand,” Greenwald said.

Key said on Wednesday it should be no surprise that the GCSB was monitoring foreign countries, but would not be drawn on the details. “I’m not going to go into who we gather intelligence on or why,” he said.



“In the end NZ does gather foreign intelligence, but for good reasons, and lawfully.”



Australia became embroiled in a diplomatic crisis in October last year, after Guardian Australia revealed that intelligence officials had tapped the phones of Indonesia’s outgoing president, Susilo Bambang Yudhoyono, his wife, and member of his inner circle.