American whistleblower Edward Snowden says the United States has pressured New Zealand to change its laws to enable mass spying on citizens.
Mr Snowden made the claims in his testimony to the European Parliament.
The former US National Security Agency contractor fled the US last year after leaking thousands of documents that revealed his employer's extensive surveillance programmes. He faces spying charges in the US, but has been given asylum in Russia.
Mr Snowden says the NSA has a foreign affairs division which searches for loopholes in other countries' laws to justify indiscriminate, mass surveillance.
Such operations have occurred recently in Sweden, the Netherlands and New Zealand, he claims.
The Green Party says methods described by Mr Snowden to the European Parliament would give governments the ability to deny they are spying on their own citizens and the testimony is disturbing.
Co-leader Russel Norman told Radio New Zealand's Checkpoint programme on Tuesday that, even as a member of Parliament's Intelligence and Security Committee, he is not privy to this kind of information.
"It's pretty limited and they have a lot of powers to refuse to answer questions and, of course, there's a Government majority on the committee and the minister responsible for the agency, the Prime Minister, chairs the committee. So it's a very constrained committee."
Dr Norman says there are ways to get around agreements countries like New Zealand and Australia have about accessing their own citizens' data.
"If you think about the cable between Australia and New Zealand - if you have that agreement with New Zealand at one end and a mirror agreement with Australia at the other, basically if you're tapping both ends of the cable you can collect all the data on all Australians and New Zealanders by having this patchwork of agreements around the world."
The Office of the Prime Minister said on Tuesday there would be many leaks from Mr Snowden in the coming months and he can't comment on them all. In the past, John Key has said New Zealand intelligence agencies act within the law when carrying out surveillance.