On Thursday, Mr Carr and other AUKUS critics gathered in the Kiwi capital to rail against New Zealand's involvement in the military pact.

Mr Carr, Australia's foreign minister from 2012-13, joined with former prime ministers Helen Clark, of New Zealand, and Enele Sopoaga, of Tuvalu, to argue AUKUS makes the Pacific less safe.

The primary AUKUS pact sees Australia receive nuclear-powered submarines from the UK and US in an attempt to shore up Australian security at a cost of hundreds of billions of dollars.

The New Zealand government is actively considering membership of pillar two of the alliance, as are like-minded countries such as Japan, South Korea, and Canada.

Pillar two would see AUKUS members develop and share advanced military capabilities such as AI, quantum and hypersonic technologies.

Mr Carr said the secondary pillar was "concocted" to "rope (others) in to an anti-Chinese alliance".

"I don't want to appal the diplomats present by using a vulgarism but it's pure bulls**t .... pillar two is fragrant, methane-wrapped bulls**t," he said.

"Why do I call it bulls**t? Because it has been cobbled together to make it look like there is more to AUKUS than subs. There isn't."

The former NSW premier argues it is folly for the US to pursue a foreign policy based on securing "primacy", and Australia is aligning itself too closely with the US in its great power rivalry with China.

Ms Clark, a proud champion of New Zealand's independent foreign policy both during and after her prime ministership, agreed the question of alignment was central.

"We have to weigh up where we position ourselves as tensions have risen considerably between the US and China," she said.

Ms Clark argued for New Zealand to take a position of de-escalation of US-China tension, and de-militarisation in the Pacific.

"What is good about the ratcheting up of tensions in the region? Where is the military threat for New Zealand? What does AUKUS pillar two actually offer New Zealand?" she asked.

"Do we really need access to quantum technology for military purposes, an offensive cyber weapons capacity and hypersonic weapons?"

The event was endorsed by the New Zealand Labour party, with leader Chris Hipkins introducing Ms Clark and saying the forum would influence his party's policy.

Mr Hipkins' Labour government was also investigating membership of AUKUS pillar two but the party has abandoned its support since entering opposition last year.

"The new coalition government seems to be rushing headlong into (AUKUS pillar two) without any electoral mandate to do that, without clearly articulating what it is they think they are signing us up to," Mr Hipkins said.

The coalition government, led by Chris Luxon and with Winston Peters as foreign minister, argue they have not decided whether to join up, and are merely continuing to explore membership, just as Labour did in government.

Privately, government officials are flabbergasted by Ms Clark's intervention, believing she is jumping at shadows and attempting to control Labour's foreign policy direction.

Mr Peters says it is not yet clear whether AUKUS members are open to having New Zealand as a member.

While in Wellington, Mr Carr also criticised Scott Morrison, the Australian architect of AUKUS, and his successor Anthony Albanese, for continuing support for the pact.

"Scott Morrison settled on AUKUS as a way of dividing the Labor party and seeing Labor isolated in the lead-up to an election," he said.

"Labor - in what could be the biggest mistake by the Albanese government - didn't say 'we're going to have a review, a review of the cost ... and not a review of the opportunity cost."

Mr Carr says the $386 billion cost to Australia could have delivered many more conventionally powered submarines, and represented "the biggest transfer overseas of Australian wealth in our history".

Australian Associated Press