Campaigners against seabed mining in the Cook Islands have slammed a series of meetings held across Australia and Aotearoa-New Zealand informing the Pacific nation's diaspora about the future of their ancestral homelands as misleading.

The meetings involved Cook Islands Prime Minister Mark Brown and advocates of the controversial but lucrative practice.

While just 15,000 residents live in the Cook Islands, more than 80,000 citizens and descendants reside in Aotearoa and a further 30,000 in Australia.

The anti-seabed mining camp suggested supporters of the proposal had been planted in the audience to shut down opposition, while opponents were given little notice of the dates of the community meetings.

A leading opponent left a meeting in Sydney calling for greater transparency and more genuine consultation over the government's seabed mining plans.

However, international media sources have reported government documents were signed in February, raising doubts over whether feedback from meetings will make a difference to the Cook Islands government's decision.

Helena Keenan-William, a supporter of Protect Our Ocean Environment - Cook Islands action group, believed the "last-minute" public meeting made Cook Islanders wanting to travel from throughout New South Wales to Sydney confused and concerned of the motives behind the apparent short notice.

"I was only made aware of the event two days before it even happened, which was astonishing to me," she told PMN Cook Islands radio.

"The presentation was overcrowded with people selling a point. I felt like I was in a car sales gimmick."

A 11-member delegation which included Mr Brown allegedly lacked any scientific or academic expertise, according to Ms Keenan-William, and appeared as if they were already involved in the early stages of the project.

The practice of seabed mining involves the collection of polymetallic nodules on the bottom of the ocean floor. The mineral concretions form concentric layers of iron and manganese hydroxides at its core.

As nodules can be found in vast quantities and contain valuable metals, deposits have been identified as a potential economic benefit to several Pacific Island nations.

"The hosting of (the meeting) all was just in shambles...I had very little time to prepare notes or to ask the right questions," Ms Keenan-William said.

"I want to be shown this is what we're doing, this is how, and this is our contingency plan.

"The seabed authority or the group of professionals presented to us weren't specialists (nor) environmentalists. The group was made up of bishops and the everyday Cook Islanders."

Ms Keenan-William said the delegation told the audience the project status is in its "beginning phase" of mining efforts.

Fishing has allegedly been prohibited in several spots around the Cook Islands for the benefit of the seabed mining industry, she claimed.

The government has told Cook Islanders seabed mining will be the silver bullet for its economy which holds free association and relies heavily on financial assistance from Aotearoa-New Zealand.

"There's been a lot of what I call 'elder mind-planting', spreading a lot of misinformation, and leaning the culture to believe that this is a completely non-invasive, easy way to make money," Ms Keenan-William said.

"But we know from science, data and research collected since the '60s that this simply isn't true."

A 2019 research survey from Ocean Minerals LLC – a US mining company which also owns the Pacific-based Moana Minerals – is one of three companies with exploration permits for deep-sea mining in the Cook Islands.

Another permit has been handed to a firm from China amid tensions over the burgeoning Chinese influence in the Pacific.

Ms Keenan-William says language accessibility was also an issue at the Sydney meeting.

Complaints were made that most of the dialogue of the meetings was intentionally conducted in Cook Island Māori and/or in Pukapukan dialect – and not in English, which is an official language – to isolate Cook Islanders, especially younger generations who were born or raised in Australia.

"(This) was clearly aimed at Cook Islanders of an older generation," she said.

"How are you supposed to educate and advise us if not all of us can connect to it?"

Ocean Ancestors spokesperson Louisa Castledine spoke out at the recent Gold Coast meeting saying seabed mining is not regenerative nor sustainable, saying it is destruction which is dressed up as progress.

Research has indicated the nodules could be used towards the militarisation of nuclear weaponry.

"I am a Master's student here in Australia, studying Indigenous-led social equity, which looks at the outcomes of Indigenous people throughout the world," Ms Castledine told the meeting.

"My concern is that we, as a country, don't exercise enough sovereignty and agency over our ocean to commandeer the majority of that economic benefit."

The official response from the Seabed Minerals Authority to the Cook Islands News called the face-to-face sessions as presenting a "science-led, environmentally responsible, and sovereign approach to seabed minerals exploration".

The authority characterised community engagement as a "next step" to strengthen relationships between government and the diaspora, clarifying what is happening and what is not.

Mr Brown labelled environmental groups opposing the measures as "ideological", reiterating no mining has been approved and all current activities are solely exploratory.

"These conversations reaffirm who we are and what we stand for", the PM told the Cook Islands News.

"Our diaspora carries our culture and pride with them. They are part of our national direction, and their voice matters."

Cook Islands Opposition leader Tina Browne called for a "national pause" to ambitions of deep sea mining, warning by charging ahead the country would risk its oceanic heritage and identity over a decision which could have irreversible consequences.