The Australian government is giving its strongest indication so far that it will take action against China at the World Trade Organisation, but Prime Minister Jacinda Ardern says it's too early to say whether New Zealand will back them.
In May, China began threatening to slap tariffs on the barley industry, as a result of "an ongoing anti-dumping and countervailing duties investigation".
Australia's Minister of Trade Simon Birmingham has detailed appeals the government has made through China's domestic processes to overturn the decision and limit the impact on the $A1.5 billion ($NZ1.58 billion) barley trade with China.
"We sought to engage in good faith," Birmingham told the ABC's Insiders programme on Sunday.
"We are disappointed that all the evidence, as compelling as we are confident it is, was rejected by the Chinese authorities and that appeal was unsuccessful."
Birmingham said the WTO appeal was the next step.
A professor of international law is calling for New Zealand to back Australia in its claim at WTO if it proceeds.
Waikato University Professor Alexander Gillespie said that China's tariffs on Australian goods escalated quickly after having started off informally and on a lower scale.
"The dispute between China and Australia is much more difficult than the dispute with a lot of the other countries that New Zealand is allied with. They have disputes over security, they have disputes over the way Australia spoke up over the World Health Organisation and the need for an independent inquiry [into Covid-19] and Australia has been much more aligned with what Donald Trump had to say. So China has put a lot of attention on them.
"Nonetheless, we do stand for the rule of international order and law and we should support Australia in this effort."
Gillespie said that backing Australia was likely to anger China, "but if you don't stand up for the rules of international law and order right now, you could be the next one in line".
"So you've got to make a stand, and it's not about whether Australia is right or wrong, but it's about having the matter dealt with at an international level for a tribunal to see the merits of the case."
However, Ardern said she required more official advice and information before making any commitments like that, because it had only recently been put to her.
"I don't want to make statements on that without actually having seen what specifically has been put to the WTO," she said.
"However, we have an expectation that the rules of the WTO and the agreements that we are held to are upheld, because of course it's an incredibly important institution for us and we expect those rules to be followed by those we trade with."
She said the implications of the wine tariffs for Australia were greater than what would be for New Zealand.
"[For Australia], it's one of their biggest markets for wine as an export for them - not to the same degree for New Zealand. China is our eighth largest wine export market. It's only taking about two per cent of our total exports so we're in a different category there."