New Zealand Prime Minister John Key on Monday invited Chinese officials to quiz him about reports that Wellington worked with US intelligence on a plan to hack Chinese diplomatic communications.

Beijing expressed concern at the claims, which are based on documents from US whistleblower Edward Snowden obtained by Auckland's Herald on Sunday newspaper.

The newspaper reported that New Zealand intelligence and the US National Security Agency (NSA) collaborated on a plan to hack a data link between China's consulate in Auckland and a nearby visa office run by the Chinese.

It said it was unclear whether the hack went ahead because Snowden fled the NSA in May 2013, before it had come to fruition.

"China is deeply concerned about the relevant report," Chinese foreign ministry spokesman Hong Lei said at a regular briefing in Beijing.

"We strongly urge relevant countries to immediately stop undermining the interests of China and other countries through the usage of the Internet."

Key refused to comment on the newspaper report, saying only that the documents it was based upon had been stolen.

"I'm not going to talk about any foreign intelligence that we gather from any country or any particular reason, all I can tell you is that we gather information when it's in the best interests of New Zealand," he told TV3.

He refused to speculate on whether the issue could damage relations with China, New Zealand's largest trading partner.

"You're asking a hypothetical question and I'm not going to do that because I can't give you an answer, I don't know," he said.

"What I can tell you is we've got an immensely strong relationship with China, it's very open and we talk to them about all sorts of things.

"If they want to raise any issue with us they're welcome to, but I'd be surprised if they do."

New Zealand is part of the "Five Eyes" intelligence network which also includes the United States, Britain, Australia and Canada.

Snowden documents released last month alleged Wellington was conducting mass surveillance on its South Pacific neighbours and passing the information onto its Five Eyes partners.