Anthony Albanese will join regional leaders at the Pacific Islands Forum as tension begins to show over New Caledonia.
The Australian prime minister arrived in Tonga late on Tuesday, joining other leaders from the 18-nation bloc after two days of the summit.
"It's fantastic to be here, the Pacific Islands Forum is such an important gathering," he said from the tarmac at Nuku'alofa International Airport.
"We're part of the Pacific family and over the next couple of days we'll be talking about our common interest, how we can work together to combat climate change, for economic development and for peace and security."
Mr Albanese will take his place in formalities from Wednesday morning, joining Pacific Minister Pat Conroy who flew Australia's flag on a challenging first day.
"We experienced yesterday the crises we're facing in the Pacific ... a torrential downpour and then a 6.8 Richter scale earthquake in one day," he told the ABC.
For the most part, leaders have displayed a regional unity in Tonga that PIF authorities have craved after a tumultuous few years.
However, on the hot-button issue of the New Caledonia, splinters are plain.
The future of the Melanesian nation remains clouded, months after mass pro-independence protests over voting reforms from its colonial power produced deaths and widespread damage in the capital Noumea.
In Nuku'alofa, France's Pacific Ambassador Veronique Roger-Lacan has tread on Pacific sensibilities.
Ms Roger-Lacan told leaders that PIF appeared divided on whether a fact-finding mission involving PIF leaders should go ahead, provoking New Zealand deputy prime minister Winston Peters into a sharp response.
"I suggest that the ambassador get in contact with her boss now and again when she's making those sort of comments, because they're not helpful," Mr Peters said.
In reality, the PIF mission was spiked by Paris - according to officials - which insisted on sign-off over who they met, and French observers sitting in on meetings.
In Tonga, the sub-regional Melanesian Spearhead Group - which includes New Caledonia - met on Tuesday afternoon to consider their position.
The MSG has been a proponent of an independent New Caledonia, led by its Indigenous Kanak people.
Moetai Brotherson, president of another another French overseas territory, French Polynesia, also sounded attacked France's handling of the crisis.
"France has always had problems with decolonisation and the road to self-determination," he said.
"They definitely have to change the way they read the situation ... they have to trust the voices of the Pacific about those issues more than their own diplomacy."
The central discussion on New Caledonia is being saved for Thursday, the all-day closed door gathering which Mr Albanese and his counterparts will attend.
Other regional heavyweight leaders Jeremiah Manele, of Solomon Islands, and Chris Luxon of New Zealand, are attending their first PIF summit, and caught in controversy.
Mr Manele is reportedly seeking to exclude Taiwan, a dialogue partner, from future meetings.
The Australian reports Mr Manele, who will host the next year's meeting in Honiara and become PIF chair, is doing so under pressure from China.
That move is destined to fail as three members maintain diplomatic ties with Taipei, and PIF decisions are made by consensus.
Mr Luxon, elected as prime minister in 2023, has set off alarm bells in the Pacific with his push to reopen New Zealand waters to oil and gas exploration.
Earlier on Tuesday, United Nations Secretary-General Antonio Guterres released a report showing the stakes for the Pacific of unchecked global warming.
Pacific leaders are unsupportive of plans by any country to expand their fossil fuel footprint.
"I'm sure New Zealand will not be ignorant of the fact New Zealand need to be responsive to the climate change issues," Papua New Guinea Prime Minister James Marape said.
"They live in the Pacific like we live in the Pacific."
