The Māori Party is not ruling out walking away from its coalition with National over the failed Kermadec discussions.
Māori Party co-leader Marama Fox is adamant they're sticking around to talk it over, for now.
"Yes, they've compared it to the foreshore and seabed and we have said it is serious enough to give us grave concern," she said.
"We want to make sure that we have explored all the options available to us before we walk away."
Court action will continue over the controversial Kermadec ocean sanctuary with Māori and the Government still at a stalemate over fishing rights.
The Māori Fisheries Trust, or Te Ohu Kaimoana, is contesting what would be 620,000 square kilometres in the northeastern corner of New Zealand's exclusive economic zone.
A Treaty of Waitangi settlement gives iwi the rights to fish in the area under what's known as the 1992 Sealord deal.
"The seriousness of this issue centres around the fact that we have a Treaty agreement that in this case we believe is being breached and if you can do that to this agreement you can essentially do that to any Treaty agreement," Ms Fox said.
Prime Minister John Key said while discussions with Te Ohu Kaimoana had failed, the dialogue with the Māori Party over the deal would continue.
"We're going to restart discussions with the Māori Party and see whether we can find a way through where they might be able to support that so it's just going to take a bit longer," he said.
Māori Party co-leader and Minister for Māori Development Te Ururoa Flavell acknowledged this was pretty much the closest they've come to walking away from their confidence and supply agreement with National.
"It is serious. It's at the very high end, but we have an agreement from the Prime Minister now," he said.
"The Prime Minister gave a commitment that he would move into further negotiations down the line."
Mr Key announced the Kermadec sanctuary proposal at the United Nations General Assembly in September 2015, to the surprise of many.
In March, Te Ohu Kaimoana announced it'd take the Government to court over the plans in which they weren't consulted.
But the Government maintains they haven't fished there for around a decade, and any fish in the area are migratory species.
The group had scheduled a news conference for 5pm on Monday hoping for talks to have reached a conclusion, but it was postponed until Wednesday morning.
On Wednesday, the group said it was "extremely disappointing that talks with the Government have been unable to resolve major Treaty differences".
"The Crown has never asked Māori whether we consent to these rights being extinguished and we reject to being treated to disrespectfully," Te Ohu Kaimoana chair Jamie Tuuta says.
"Had Māori been asked for their view on the proposal before the Prime Minister surprised everyone with his international announcement, we could have entered into a sensible discussion about its impact on Māori rights and how it could have been accommodated in a way which allowed both Treaty partners to support the proposal."
"If this had happened, the sanctuary could truly have been Aotearoa's gift to the world. Now it is John Key's and Nick Smith's."
Mr Tuuta says they tried to compromise where iwi would "voluntarily shelve the use of Māori fisheries quota in the Kermadec region while maintaining extant fishing rights".
While that option would have still needed iwi quota owners to agree, the trust thought it was a "constructive and reasonable" solution.
The group had drafted an amendment to the proposed Bill with their compromise, but says Environment Minister Nick Smith "changed the text to explicitly exclude ongoing use of the quota".
"Unfortunately, the minister accepts nothing but legal nullification of all Māori rights in the Kermadec region."
Mr Tuuta says the plan to take away Māori rights without consent "in the face of clear Māori opposition" will be a stain on the Government.
"We want all New Zealanders to know it was the Crown who walked away from this full and final settlement, not Māori.
"This will be the Government's foreshore and seabed. They are taking away real rights that are an important part of the first Treaty settlement and thereby risking every Treaty settlement that follows."
Iwi and the trust still back the idea of protecting the marine environment, but not at the cost of their fishing rights.
The outcome of the talks seemed relatively clear on Monday, with Mr Key indicating there'd only be a couple of things "at the margins" which could be compromised.
The Government was steadfast in its mission.
Dr Smith says he's disappointed at the outcome following 10 meetings over 10 months, but he defended the Government's position.
"The claimed consequences for Te Ohu Kaimoana are way overstated. Māori have caught more than three million tonnes under the fisheries settlement since 1992, but not a single tonne in the Kermadecs. There are five fishing companies affected, none Māori, but who collectively have only caught about 20 tonne per year, out of an annual total fishing industry catch of 450,000 tonnes."
He says it doesn't undermine the Sealord Deal.
Labour's Treaty of Waitangi negotiations spokesperson Nanaia Mahuta says the Government has failed to honour their commitment to Māori.
The party supports the sanctuary, but has "serious concerns" about the Government failing to consider Treaty rights.
"The loss of Treaty settlement assets and quota rights is an important matter of principle. The Minister should never have removed the right to claim compensation in court and we recognise that the broader fishing industry are challenging this decision," she says.
Last week at the World Conservation Congress in Hawaii, the International Union for Conservation of Nature voted to set aside 30 percent of the world's oceans as "highly protected" by 2030.