Spy agency boss Warren Tucker should come clean and clearly state the benefits to New Zealand of being part of a United States-led spying network, the Green Party says.

Dr Tucker, director of the Government Communications Security Bureau (GCSB), today challenged claims that New Zealand was a lackey of the United States and that former prime minister David Lange was kept in the dark by intelligence officials.

The country benefited from its role in the Echelon communications interception network, which also includes the US, Australia, Britain and Australia, he said. The partnership gave "a direct line into the inner circles of power in London and Washington".

But Green MP Keith Locke today said that if Dr Tucker was so clear about the exact benefits, then he should share them with all New Zealanders.

"I'd challenge him to make them public, because I think if you weighed it all up, you'd find there are more negatives than benefits," he said.

Taking part in the network meant New Zealand was serving US foreign policy objectives, which were often quite different from our own, according to Mr Locke.

Dr Tucker, writing in The Dominion Post and The Press newspapers today, also said the GCSB Act made it clear that the agency could not spy on New Zealanders.

But Mr Locke said the Act was not as black and white as Dr Tucker was suggesting.

While the agency was focused on intercepting foreign communications, many communications going to the Pacific Island nations, which have been targeted by the GCSB, would be coming from New Zealanders.

The Act also allowed the agency to spy on subsidiaries of multinational companies and organisations.

That would include a multitude of local companies such as foreign-owned banks.

It could also include the local arms of international pressure groups such as Greenpeace and Amnesty International.

Mr Locke repeated his call for a full inquiry into the agency's role.

He also made the call after the accidental release of the agency's 1985-1986 annual report, which was included in a box of Mr Lange's papers held in Archives New Zealand.

The report showed New Zealand had spied on friendly countries such as Japan and several Pacific Island nations, and the United Nations.

Mr Locke said in the cold-war period there had been a rough national consensus on which countries should constitute an intelligence target.

"But now some people believe we should align ourselves with the United States, while others believe we should be more closely aligned with Europe. There's no clear consensus."

An inquiry would not need to touch on operational details but a debate on who the agency should be spying on would help shape a consensus view.