Updated

New Zealand knows of Al-Qaeda-trained activists within the country who need to be monitored, Prime Minister John Key said Thursday amid debate on the need for stronger spy laws.

Key took to the airways to defend legislation that allows the country's intelligence agency to spy on local residents, saying opponents refused to acknowledge security threats were genuine and needed to be addressed.

"In the real world, in New Zealand, there are people who have been trained in Al-Qaeda camps," he told commercial radio.

"(People) who operate out of New Zealand, who are in contact with people overseas, who have gone off to Yemen and other countries to train. That's the real world, the reality of what we're dealing with."

Key did not provide any further details on the potential Al-Qaeda threat in the remote South Pacific nation, which sent a small military force to Afghanistan but played no part in the US-led invasion of Iraq.

New Zealand's intelligence service, the Government Communications Security Bureau (GCSB), is currently barred from spying on New Zealand citizens or residents.

Key wants the restriction removed, saying it needs to cooperate more closely with agencies such as the police and military in an increasingly complex cyber-security environment.

Groups ranging from the Law Society to Internet giants Facebook and Google have raised concerns about the proposal, while "hacktivist" group Anonymous crashed Key's website this week in protest.

One of the strongest opponents is Megaupload founder Kim Dotcom, who received an apology from Key last year after revelations the GCSB illegally spied on him before he was arrested for alleged online piracy.

The Auckland-based German national mocked Key's assertion, suggesting Al-Qaeda's presence in New Zealand was most likely limited to "Kiwi kids watching 'how to make a bomb' on YouTube's terrorist channel".

"The only terrorists living in New Zealand are those who terrorised my family to impress Hollywood and the White House," he tweeted, referring to the armed police raid on his Auckland mansion in January last year.

The Green Party accused Key of scaremongering in an attempt to justify changes that would have a "chilling" effect on the privacy of New Zealanders.

"John Key is trying to frighten the New Zealand public into submission as he pushes through his law to strip away their rights," Greens co-leader Russel Norman said.

The spy bill is currently being debated by parliament, where it is expected to pass by a single vote.