The Government could "ultimately" pass legislation to nationalise water but Prime Minister John Key says he doesn't believe it's necessary.

Key has rejected calls for a national settlement on water after a hui of more than 1000 Maori last week said the Government must negotiate a national framework for recognising Maori rights and interests before selling shares in four state-owned power companies.

The hui, convened by Maori King Tuheitia, has warned Maori will take a challenge to court if the Government continues with its programme which the Waitangi Tribunal has said would breach the Treaty of Waitangi.

In July, Key said the Government would not use legislation to override Maori interests in water with foreshore and seabed-type law.

Today he said the Government "could ultimately pass legislation" to nationalise elements such as water and wind.

"We've nationalised oil and gas and other resources back in the late 30s," he told TVNZ's Breakfast programme.

"I don't think that's necessary and I think my view is widely held by a lot of New Zealanders. If it was holding New Zealand back, sure we could arguably go and do that but that's not where I see these things going."

The Government insists no one owns water despite King Tuheitia last week claiming it was owned by Maori.

Key rejected claims by King Tuheitia's spokesman Tuku Morgan that he was "culturally ignorant".

"He can make any claims he likes. The Maori King entitled to a different view to mine, it doesn't mean I'm culturally ignorant."

No "particular group" owned natural resources such as water, fire, air and wind, which were available for the mutual benefit of all New Zealanders, Key said.

Key said he wouldn't recognise the view of the hui and the Maori Council which took a claim to the Tribunal.

"I don't think it's right. If someone wants to take that land grab, they can give it a go," he told Radio Live.

The Government couldn't find any merit in the Tribunal's recommendation Maori be offered "shares plus" in the power company floats which could include veto rights, but Key denied its five-week consultation process with affected iwi was a farce.

"We are open minded, if we missed something, and iwi are coming up to us and saying 'here's a different perspective', then of course, we'd look at that," he told Newstalk.

The unity of the national hui has already been challenged by the Iwi Leaders Group which has been negotiating with the Government.

Key refused to attend the hui and forbid National's Maori MPs to attend.

Earlier this month the row over water rights forced the Government to announce it was delaying the first of its partial asset sales, Might River Power, until next year.

- © Fairfax NZ News