Pacific Islands Forum secretary general Henry Puna says the region's reunification will soon be sealed, putting to an end regional squabbles.

Pacific leaders have gathered in Fiji this week after Prime Minister Sitiveni Rabuka called a special leaders retreat.

The goal of the retreat is to welcome Kiribati back into the fold, ending a long-running spat that saw Micronesia walk away from the forum.

As PIF chair, Mr Rabuka has brokered a deal with the Pacific sub-region to that delivers more power and positions to Micronesia.

One such offering is the chance to name the next secretary general when Mr Puna retires in 2024.

Palau president Surangel Whipps Jr told Radio NZ their choice will be former Nauru president Baron Waqa.

Mr Puna is at the heart of the Pacific splintering, after taking the job which Micronesia believed was due to rotate to their region.

He told AAP he was "absolutely happy" with the pact, as the 18 leaders began talks in Nadi to solidify the deal.

"We're now complete as a family," he said.

"Fingers crossed everything will ride smoothly tomorrow."

Mr Puna greeted Kiribati president Taneti Maamau with a hug on his arrival at the glitzy Sheraton Fiji Golf & Beach Resort, which is hosting the retreat.

The key question now is whether this new pact will hold, or will new ructions come to the fore.

Australia and New Zealand, the two regional powerhouses, are among the few countries not to send their leaders.

Australian prime minister Anthony Albanese has dispatched Foreign Minister Penny Wong for her ninth visit to the Pacific since taking office less than nine months ago.

Before touching down in Fiji she visited Kiribati, meeting Mr Maamau and signing a strategic tie-up.

Under the deal, Australia will gift Kiribati a patrol boat, its second in two years, upgrade police facilities and personnel, and help build a wharf.

"We really are very pleased that Kiribati is returning to the PIF, we think we're stronger together," Ms Wong said in Nadi.

NZ prime minister Chris Hipkins will also miss the occasion, with deputy Carmel Sepuloni to attend in his place.

Ms Sepuloni is the most senior government leader of Pacific descent in NZ's history.

"We have a fantastic relationship and want to make sure at we are good partners to Pacific island nations," she told AAP.

"I think we are trusted in the Pacific.

"Clearly, there are some areas that are priority for the Pacific that are a priority for us - Pacific resilience and things like climate change - and so we'll continue to work on those."

Leaders will also discuss Japan's plan to release wastewater from the Fukushima nuclear power plant into the Pacific Ocean.

Japan wants to release more than one million tons of water contaminated in the 2011 disaster, which was caused by a magnitude 9.0 earthquake.

While Japan has treated the water, many in the Pacific - which has a painful history of nuclear testing - want assurances of safety.

Incoming PIF chair, Cook Islands prime minister Mark Brown, led a delegation to Japan earlier this month and will report back to the leaders' retreat.

Ms Sepuloni said NZ stood alongside the Pacific.

"What we've seen in science so far shows that what is happening is safe ... we've been given that assurance from Japan and that is what the Pacific leaders collectively have wanted to see," she said,

The meeting also marks the formal handover of the chair from Fiji to the Cook Islands.