The Pacific Islands Forum (PIF) faced the prospect of a mass walkout Thursday by five Micronesian nations angry over a leadership snub, risking instability in a region where China is vying for influence.

The five countries argued it was their turn to select the PIF secretary-general under an informal arrangement that has stood for decades, but their preferred candidate failed when former Cook Islands prime minister Henry Puna won a ballot for the post by a single vote.

The PIF is the Pacific's leading regional body, mostly made up of small island states along with Australia and New Zealand, and is a key element of Canberra's diplomatic efforts in the region.

"What we have seen is a failure of the Pacific way," Federated States of Micronesia President David Panuelo told the Australian Broadcasting Corporation.

He said Puna's election was a slight to small north Pacific island states by their larger and more influential neighbours in the south.

"What we have seen is a south Pacific that looks down on the north Pacific and we find that deeply unfortunate... it's a huge fracture in the (PIF's) unity and spirit of cooperation."

Although the Micronesian countries do not share a unified stance on Beijing, a split in the PIF's ranks could provide an opening for China to boost its influence with the sparsely populated but strategically important island nations.

The PIF is the Pacific's leading regional body, mostly made up of small island states along with Australia and New Zealand
The PIF is the Pacific's leading regional body, mostly made up of small island states along with Australia and New Zealand AFP / Mike LEYRAL

The five nations -- Palau, the Marshall Islands, Kiribati, Nauru, and the Federated States of Micronesia -- warned ahead of the meeting that they would consider withdrawing from the PIF unless they were allowed to pick the secretary-general.

Puna argued the coronavirus crisis meant convention should be ignored in favour of good leadership, a stance backed by PIF chairman Kausea Natano.

"Puna assumes the position of secretary-general at a critical time in the region's history and will need to guide the region through the Covid-19 recovery," he said.

Natano insisted the divisions stirred up ahead of Puna's election had been healed and the PIF was united behind the new secretary-general, who stepped down as Cook Islands prime minister last year after almost a decade in charge.

But Micronesia's Panuelo warned the threat to leave remained and the five nations would meet "very soon" to discuss what action to take.

He said if the Micronesia region was overlooked for senior roles "then there's really no reason to remain in the Pacific Islands Forum".

Palau president Surangel Whipps was also talking tough.

"Clearly there is no need really for Micronesia to be part of them, they don't really consider us part of them," he said.