Australia, New Zealand and Pacific nations have signed a declaration highlighting climate change as "the single greatest threat" to Pacific people, while island nations called on the United States to return to the Paris agreement.

Key points: The declaration expands the idea of regional security to include environmental issues

The declaration expands the idea of regional security to include environmental issues It specifically names climate change as the region's "single greatest threat"

It specifically names climate change as the region's "single greatest threat" It recognises that the Pacific is "increasingly crowded" in terms of geopolitics

The communique was signed at the end of the Pacific Islands Forum in Nauru, attended by large and small island states as well as New Zealand's Prime Minister Jacinda Ardern and Australia's Foreign Minister Marise Payne.

But there was last-minute wrangling over the language on climate change, with some Pacific nations privately accusing Australia of trying to water down the final declaration from leaders.

Australia would also not back a statement from small island states which calls for countries to "urgently accelerate" reductions in carbon emissions.

Tuvalu's Prime Minister Enele Sopoaga didn't directly name Australia, but when pressed by journalists confirmed a country "starting with a capital A" had objected.

"The issues are so critical for leaders of smaller island states because of their vulnerability to climate change," Mr Sopoaga said.

"We appealed to Forum leaders to endorse [the statement] so we can walk the talk."

Anger persists over behaviour of Chinese 'nobody'

Sorry, this video has expired Nauru's President Baron Waqa slams Chinese 'nobody'

In the final communique, Australia and New Zealand also did not join a call from other Pacific Island Forum members for the United States to re-join the Paris climate change agreement.

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Washington formally announced it would withdraw from the landmark climate agreement in August last year.

The Boe Declaration is named after the district in Nauru it was signed in.

It declares that climate change "remains the single greatest threat to the livelihood, security and wellbeing of the peoples of the Pacific".

Leaders also signed a communique saying they would work together in the lead-up to this year's COP24 climate conference in Poland, in order to "ensure effective progress on Pacific priorities with regards to the Paris Agreement".

Meanwhile, Nauru's President Baron Waqa is still fuming about his row with a Chinese diplomat earlier this week.

China's representative at PIF walked out of a meeting after being denied an opportunity to address leaders about climate change.

Marise Payne's handprint in stone to sign off on Boe Declaration. ( Supplied: Australian Conservation Foundation )

Mr Waqa lashed out at the official during the meeting's final press conference, and said Nauru would try to escalate the dispute.

"Would he behave like that in front of his own President? … You look at him, he's a nobody!" Mr Waqa said.

"We won't just seek an apology, we'll even take it to the UN."

Tensions first flared when Chinese officials were unable to enter Nauru on diplomatic passports.

Nauru is one of the Pacific nations which recognises Taiwan rather than Beijing — and the episode highlighted the way their contest for influence can stir conflict in the region.

Pacific 'increasingly crowded and complex'

Senator Payne (with New Zealand foreign minister Winston Peters) also announced a new information-sharing initiative for the region. ( Pool Photo via AP: Jason Oxenham )

The Boe declaration recognises the Pacific's "dynamic geopolitical environment", which was leading to "an increasingly crowded and complex region".

China's increasing presence in the region has been in the spotlight in recent months, especially its loans for large-scale infrastructure projects in island nations.

Australia has been seeking to reassert itself as the "partner of choice" for Pacific countries.

Foreign Minister Marise Payne announced that Australia would also work to establish a new centre focused on "strengthening the ability of Pacific governments to enforce their laws and protect their sovereignty."

Senator Payne said the new Pacific Fusion Centre, to be established in mid-2019, will provide Pacific decision makers with information needed to better identify and respond to security threats, such as illegal fishing, people smuggling and narcotics trafficking.

In addition to the new centre, Senator Payne said Australia would help provide strategic policy development in the region with a new Australia Pacific Security College, to be established in early 2019.