The Waitangi Tribunal says the sale of shares in some state owned assets must be delayed, until Maori water rights are resolved.
In findings released on Friday, it says the Crown would be in breach of the Treaty of Waitangi if it proceeds with the partial sale of state-owned power generators without recognising Maori rights to water.
It also says Maori culture cannot be relegated and ignored.
The findings are in an interim report on the Maori Council's urgent claim on water rights.
The claim was filed over the Government's plans to sell stakes in hydro-power generators, with the claimants arguing the water going through the turbines would effectively be commercialised.
But the tribunal doesn't close the door on the sales, suggesting a solution could be found to press ahead with floating shares, starting with Mighty River Power.
It says it's up to Maori and the Crown to devise a scheme that specifically recognises rights over the freshwater used in the three power stations private investors would buy into.
The inquiry suggests the issuing of shares to settle rights and the use of royalty payments could be discussed, but stresses that it's up to the Treaty partners to decide on a way forward.
Treaty key to findings
In delivering the interim report, the tribunal relies heavily on the Treaty of Waitangi and previous legal fights for rights.
It says if the Crown proceeds with the sell-off without recognising and resolving Maori rights, the Crown won't be able to carry out its Treaty duty to actively protect Maori property rights.
The tribunal says claimants provided conclusive evidence that hapu and iwi had customary rights and authority over lakes, rivers and streams in 1840, when the Treaty was signed.
Under Article 2, the Treaty guarantees Maori tino rangatiratanga - or full authority - over their taonga (treasured possessions).
Claim has 'long pedigree'
The report notes that this year's claim brought by the Maori Council and 10 tribes is the latest in a long series of Maori claims to legal recognition of their proprietary rights to water.
An example is Lake Omapere in Northland, where Ngaphui hapu first tried to secure legal title in 1913 but didn't succeed until 1955, after years of litigation with the Crown.
The tribunal points out that those claimants are once again in the position of attempting to get the Crown to acknowledge their rights.
It says it's satisfied that the Maori Council claim has a long pedigree.
Crown view and tribunal's hope
Prime Minister John Key has said no-one owns the water in New Zealand.
He also angered the Maori claimants by saying the Government could ignore whatever findings the Waitangi Tribunal might issue - a comment he made while the hearing was getting underway.
The tribunal's presiding officer, Chief Judge Wilson Isaac, says he trusts the interim report and recommendations will be read and considered in good faith, respecting the mana of each Treaty partner.
Another report, second hearing to come
Friday's report is a truncated version; a more comprehensive dossier is due out later this year.
The findings were rushed out because the Government asked for an early report, so it could make decisions about whether or not to proceed with the sale of shares in Mighty River Power.
While the full report is yet to come, the tribunal says its recommendations won't change.
Another stage of hearings are planned, which will examine how Maori rights in water can be reconciled with the interests held by other parties.