Former Prime Minister Sir Geoffrey Palmer says he doesn't know anything about allegations New Zealand spied on Japan ahead of an international whaling meeting he attended.

The Intercept website has published National Security Agency (NSA) documents obtained from the whistleblower Edward Snowden.

One outlines how New Zealand's Government Communications and Security Bureau (GCSB) collected information on Japan's lobbying for whaling.

That was then shared with an NSA agent before an International Whaling Commission meeting in Anchorage, Alaska in 2007, the document states.

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Sir Geoffrey attended the meeting as New Zealand's Commissioner to the IWC and told the Herald he was unaware of what was or wasn't done by the GCSB.

"There is nothing I can say usefully about it," he said. "One thing I will say is this, any intelligence about the Japanese is hardly very much use at these meetings because you know what their position is and it has been pretty much the same for many years.

"I don't want to say anything more about it because intelligence matters are not discussed and I will not say anything else."

The 77-member commission voted on a number of whale conservation measures in 2007 and Japan was lobbying other countries for votes supporting pro-whaling proposals.

"New Zealand had the target access, and collected and provided insightful SIGINT [signals intelligence] that laid out the lobbying efforts of the Japanese and the response of countries whose votes were so coveted. US officials were anxious to receive the latest information," the NSA document states.

An NSA operative would take a 30-minute taxi to the agency's local operation centre, where hard copies of the GCSB intelligence would be collected. US, Australian and New Zealand officials then viewed the intelligence in a conference room.

"We knew the delegates valued the material simply because they took time from their very hectic schedules to be there and read it," the NSA document states. "Was the outcome worth the effort? The Australian, New Zealand and American delegates would all say, 'yes'. I believe the whales would concur."

A spokeswoman for the GCSB said the agency did not comment on "speculation about matters that may or may not be operational".

Prime Minister Bill English this afternoon said he couldn't comment on any operational matters but said the GCSB had to comply with New Zealand law.

"That law has just been overhauled quite significantly with the support of the overwhelmingly majority of Parliament, and we would expect them to continue to comply with the law."

English said no contact had been made by Japan about the reports, and he did not expect it would affect any potential future visits there.

In an article after the 2007 meeting, Greenpeace hailed it as a "spectacular comeback" for anti-whaling countries, noting that Japan had in the preceding year gathered enough support to pass a resolution calling the whaling moratorium invalid, but this was no longer the case after a few of Japan's supporters switched sides.

This week, a Five Eyes intelligence conference is taking place at Millbrook Resort near Arrowtown.

Among the people attending are Federal Bureau of Investigation director James Comey and Central Intelligence Agency director Mike Pompeo.

It is understood about 15 agencies that carry out intelligence for Five Eyes - the spying partnership of the United States, Australia, Canada, the United Kingdom and New Zealand - are attending the conference.

Minister for the Government Communications and Security Bureau (GCSB) and Security Intelligence Service (SIS) Chris Finlayson's is expected to attend.