New Zealand Prime Minister Jacinda Ardern on Wednesday backed Pacific leaders' calls for urgent action on climate change, ramping up pressure on Australia to overhaul its stance on global warming.

Australia's Scott Morrison arrived at a meeting of Pacific island leaders in Tuvalu with Canberra's regional leadership in question amid intense scrutiny of his government's climate change policies.

Wealthy Australia has long dominated the Pacific Islands Forum (PIF), an 18-member grouping consisting mainly of small atoll nations dotted around the vast Pacific ocean.

But its role is in doubt after leaders of the low-lying nations questioned in recent days whether Australia's climate-sceptic leader is committed to curbing a problem they see as a fundamental threat to their survival.

Ardern joined the chorus after touching down at the PIF meeting, further isolating coal-producing Australia.

"New Zealand will do its bit and we have an expectation that everyone else will as well... Australia has to answer to the Pacific, that's a matter for them," she told reporters.

Greenpeace campaigner Joseph Moeono-Kolio said Morrison's government appeared intent on watering down the summit's communique, due to be issued Thursday, which is set to demand urgent action on climate change.

"Australia is poised to become the pariah of the Pacific," he said.

Moeono-Kolio said among the measures deemed unacceptable by Australians were calls to ban new coal mines and set a timeframe for phasing out use of the carbon-emitting fuel.

- 'Callous indifference' -

"Scott Morrison has done the exact opposite of what the leaders of the Pacific have asked Australia to do and placed Pacific communities on the frontlines of the climate crisis in an even more precarious position," he said.

"Morrison's callous indifference to the plight of Pacific islanders suggests he has no problem sacrificing entire nations for the short-term profits of his backers in the coal industry."

Story continues

Morrison has staunchly defended Australia's climate record, insisting the country will meet its 2030 emissions reduction target set under the 2015 Paris Agreement.

He also announced an A$500 million ($340 million) package this week, with funding drawn from Australia's existing aid budget, to boost climate resilience in the Pacific.

Australia and New Zealand reportedly persuaded PIF leaders to weaken the language in their communique four years ago ahead of the landmark Paris climate talks.

However, the pre-summit rhetoric from island leaders this year indicates they are unlikely to cave in to pressure from Canberra.

Australia will also be without a key ally on the climate front in New Zealand, which is now led by the progressive Jacinda Ardern rather than her conservative predecessor John Key.

"To hold a forum on an island where climate change is not a theoretical proposition but is very much a reality and a visual reality I think will be quite pointed," she told reporters.

Oxfam Australia accused Australian officials of refusing to negotiate with PIF leaders as a whole, saying they were pushing for bilateral meetings as part of a "divide and rule" strategy.

Oxfam climate adviser Simon Bradshaw said Australia was "working actively against the top priorities of Pacific Island countries" by trying to dilute the message their communique sent to the world.

"Moving beyond coal and limiting warming to 1.5C have been the most consistent and urgent requests of Pacific island countries for many years," he said.

"For the Pacific, these commitments are a matter of survival."