Samoan Prime Minister Tuilaepa Sailele has lashed out at climate sceptics and urged Australia to make deeper cuts to carbon emissions to help save Pacific Island nations from the "disaster" of climate change.

Key points: Mr Sailele says "greater ambition" is needed to stop impact of climate change

Mr Sailele says "greater ambition" is needed to stop impact of climate change He warns geostrategic competition is creating uncertainty for small Pacific countries

He warns geostrategic competition is creating uncertainty for small Pacific countries Australia, New Zealand and the US have been scrambling to reassert influence in the Pacific

Mr Sailele told the Lowy Institute in Sydney that climate change posed an "existential challenge" to low lying islands in the Pacific, and developed countries needed to reduce pollution in order to curb rising temperatures and sea levels.

"We all know the problem, we all know the solutions, and all that is left would be some political courage, some political guts, to tell people of your country there is a certainty of disaster," Mr Sailele said.

"So any leader of any country who believes that there is no climate change, I think he ought to be taken to mental confinement. He is utterly stupid. And I say the same thing to any leader here."

The Prime Minister's intervention came as some Coalition MPs press the new Prime Minister Scott Morrison to abandon Australia's promise to cut carbon emissions under the Paris agreement.

New Foreign Minister Marise Payne is also expected to face questions about Australia's climate change policies at the Pacific Islands Forum leader's meeting in Nauru next week.

Senator Payne and Pacific leaders are set to sign the "Biketawa Plus" security agreement, which declares that climate change remains the "single greatest threat to the livelihoods, security and wellbeing of the peoples of the Pacific".

Several other leaders — including Fiji's Prime Minster Frank Bainimarama and the Marshall Island's President Hilda Heine — have also called on Australia to do more to cut emissions.

Mr Sailele told the audience that "greater ambition" was needed to stop the destructive impact of climate change.

"While climate change may be considered a slow onset threat by some in the region, its adverse impacts are already being felt by Island communities," he said.

'Attempt to hide strategic neglect'

The Prime Minister also took a thinly veiled swipe at Australian anxiety about China's rise in the Pacific, warning that brewing geostrategic competition was creating enormous uncertainty for small nations in the region.

China's increasing presence in the Pacific has unnerved foreign policy officials in Australia, New Zealand and the United States, and all three countries have been scrambling to reassert their influence.

Both Senator Payne and the former foreign minister Julie Bishop have repeatedly said that Australia wants to be the "partner of choice" for Pacific nations.

Tuilaepa Sailele says the strength of leadership in the Pacific has been questioned by other countries. ( Facebook: Government of Samoa )

But Mr Sailele warned against "manipulation" of Pacific Island nations by any major power.

"The concept of power and domination has engulfed the world, its tendrils extending to the most isolated atoll communities," he said.

"The big powers are doggedly pursuing strategies to widen and extend their reach, inculcating a far reaching sense of insecurity."

Earlier this year, Mr Sailele hit out at then international development minister Concetta Fierravanti-Wells after she accused China of building "roads to nowhere" in the Pacific and burdening small nations with heavy debts.

The Prime Minister didn't name Senator Fierravanti-Wells in his speech, or single out Australia — but he made his attitude clear.

"Our partners have fallen short of acknowledging Pacific leadership," he said.

"Some might say there is a patronising nuance, believing Pacific nations did not know what they were doing, or were incapable of reaping benefits of close relationships with countries that will be in the region for some time to come.

"One has the tendency to be bemused by the fact that the reaction is an attempt to hide what we see as strategic neglect."