New Zealand will always be "predictable" in its dealings with China.

That's a promise from the Prime Minister who's flatly rejecting the most recent accusations from Beijing, as the dust settles from this week's trans-Tasman leaders' meeting.

China lashed out at the joint Australia - New Zealand statement as "irresponsible" and a "gross interference" in its internal affairs, and as containing "baseless allegations".

Jacinda Ardern and Scott Morrison released the statement after formal talks on Monday, making it clear the two countries would stand together in this challenging and volatile global environment.

The Queenstown talks were the culmination of months of commentary about the trans-Tasman relationship - had New Zealand taken a softer stance on China for the sake of trade? Had it damaged the bond with Australia?

"No", declared Morrison, with both leaders obviously keen to put paid to that narrative, backed by the statement noting concern about the South China Sea, Hong Kong and the Uyghur minority.

Ardern denied making any irresponsible comments, saying recent statements had "really just been a reiteration of New Zealand's position".

"Where we see human rights issues around the world, we as a nation will raise them. When we have concerns around whether or not trade has been conducted in a way that's following that international order, we will raise it and really in many ways it's country agnostic, that is what New Zealand does."

Again, she pushed back on the accusation of "gross interference" in China's internal affairs.

"You'll find countless examples of where this is the position that New Zealand takes internationally on the world stage, our view is that where we see issues that are different in terms of our values to our values, and we will raise it, that's part of our independent foreign policy, and it's been like that for many, many years."

Beijing's foreign spokesperson said Australia and New Zealand should not be "targeting or damaging the interests of third parties, and much less forming enclosed small clique with ideology as the yardstick".

"We once again urge relevant parties to stop making irresponsible remarks and act in ways that are conducive to bilateral relations and regional peace and stability, rather than the opposite".

New Zealand's position had been consistent, Ardern said in response.

"We have pointed out that in many ways, the way that China responds, in some cases, will have changed but our view is our relationship is a mature one.

"We will keep raising issues - often in private, sometimes in public - but we will be nothing if not predictable," she said.

Former Minister of Foreign Affairs and National Party spokesperson Gerry Brownlee said New Zealand had a "very strong relationship" with China, and trade with it was "now very, very important".

"That's all fine on one level," he said, "but we are part of a world that is recognised as the liberal democracy approach to politics, and to the way people choose the way they govern; that means that we will speak out on human rights and other abuses that we see as being inconsistent with our own thoughts and I think being able to do that is a mark of maturity between the two countries".

Brownlee also dismissed the claim New Zealand had bit its tongue on human rights to protect trade with China, saying some countries "calling us out or saying those things about us have very significant trade with China".

There was obviously "concern about the exercising of the economic might, that is now China... but in the end, we have products to sell".

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"If other countries aren't stepping up to engage in the sort of trade levels that we would like, then, of course, we're going to look for the best markets with the best prices," Brownlee said.

"One of the problems is we're used to living in a world where a rules-based approach is taken... and perhaps we're dealing with a country that's emerging as a very big economic player that doesn't quite see the rules of the world the way that we do.

"I would point out that while Australia has certainly faced some pretty pernicious levels of tariffs on the products like barley and wine, they still export about $18 billion or so worth of iron ore to China every year."

While the two prime ministers expressed their concerns about human rights, the joint statement went no further than previously stated positions. 

Green MP Golriz Ghahraman wanted New Zealand to push harder.

"This is a Government now that has received a lot of praise for 'punching above our weight' in international forums, for having a lot of soft power - we're not a superpower but maybe our super power is having a principled voice.

"And we haven't really been using it."

She hoped New Zealand would not only stand up to China, but also our closest friend and ally on issues like detainees and deportation policy.

"If we can't stand up to Australia... when are we going to stand up to anyone?"

ANZUS vs Anzac

Morrison downplayed the prospect of armed conflict with China, but when asked if Australia would expect New Zealand be on its side, said the "ANZUS arrangements were clear".

Countries like Australia and New Zealand want a "free and open Indo-Pacific", he told reporters, "where countries can trade, sovereign, resilient and to go about what they wish to pursue and their national interests for the benefit of their people, a peaceful Indo-Pacific".

"So that's what our objective is, that's what our goal is, and whether it's co-operating ourselves, and particularly through the ANZUS alliance, that is obviously guiding all ultimate decisions that are made in the context of that alliance."

Victoria University's Strategic Studies Professor Robert Ayson said the significance of that particular reference should not be ignored.

"That's not something that New Zealand ministers talk about very much. A lot of New Zealanders in the public would have thought that ANZUS is gone, but actually the ANZUS relationship between New Zealand and Australia remains very, very much there."

And he said there could be a "train of consequences", for example if there was hostile action against Taiwan by China, the United States would likely feel obligated to come to its assistance.

"If American forces were attacked by China, Australia would feel obliged under ANZUS to come to America's assistance," Ayson said.

"For New Zealand, if Australian forces are attacked in the Pacific area, the ANZUS treaty covers the western Pacific, that includes places like Taiwan Strait, or South China Sea, then ANZUS would ... come into play."

In that event "New Zealand would need to think about the obligations that had under that treaty", Ayson said.

This week's meeting in Queenstown created intense interest and commentary about the state of the relationship - Morrison will play host to Ardern at the start of next month in Australia, where once again the trans-Tasman bond will come under the microscope.