Maori Party MP Hone Harawira says the Government's support of the United Nations Declaration on the Rights of Indigenous People is more than just symbolism and it will be used to further claims of self-determination by iwi.

And Act Party leader Rodney Hide launched a stinging attack in Parliament not just on the decision to back the declaration but on Prime Minister John Key, calling him "naive in the extreme" to suggest it would have no practical effect.

Labour leader Phil Goff said the National-led Government was trying to marry together forces that were totally opposed to each other.

"What we are seeing is the impossibility of balancing out the interests between the Act Party, the Maori Party and the National Party."

He denounced the secrecy surrounding the announcement and said the Maori Party had been "duped".

The cabinet decided on March 22 to support the declaration and was informed at that time that Maori Affairs Minister and Maori Party co-leader Pita Sharples wanted to go to New York to deliver the decision.

The travel plans were kept secret - and the announcement made yesterday at 4.45am in New York.

Mr Key defended the secrecy yesterday, saying he hadn't wanted to steal Dr Sharples' thunder. He said the support of the declaration would not impact at all on New Zealand law, that it was symbolic and non-binding.

Mr Harawira, however, said "nothing is ever just symbolic for Maori".

"It is an important step in our process of heading towards self-determination. I can absolutely guarantee that those Tuhoe who are seeking sovereignty and those other iwi who will be lining up behind them will use the principles of the declaration to support their claims."

Mr Harawira said Maori up and down the country "feel a lift in Government acknowledging the rights of Maori to be human".

"This country recognises the rights of women, the rights of workers, the rights of dogs. Great that they can finally get around to recognising the rights of indigenous people."

He said Labour were "koretake [useless] bastards" who had had the chance to back the declaration but did not take it.

Mr Hide, who had a prescheduled meeting with Mr Key yesterday, said his party was "shocked and appalled".

"I am very disappointed that the Prime Minister John Key has covertly foisted the declaration on New Zealand and I consider the statement that signing this declaration has no practical effect, I consider that to be naive in the extreme."

Mr Hide also said Mr Key had "failed to honour" the no-surprises clause of the confidence and supply agreement with Act.

Mr Hide said last night that their arrangement was not in trouble, however. He said in Parliament that the declaration was divisive and a further step for New Zealand down a path of a divided nation.

"The declaration is the very antithesis of Act's policy of one law for all New Zealanders.

National, Green, Maori Party, United Future.

Labour, Act, Progressives.

About the declaration:
It is a non-binding declaration supported in 2007 by 143 countries at the United Nations. Of the four countries that voted against, New Zealand and Australia have changed their position, Canada has indicated it will support it with caveats and the United States has not signalled a change.

Contentious parts of the declaration:
* On self-government and taxation

"Indigenous people, in exercising their right to self-determination, have the right to autonomy or self-government in matters relating to their internal or local affairs, as well as ways and means for financing their autonomous functions." - Article 4.

* On a veto over the state

"States shall consult and co-operate in good faith with the indigenous peoples concerned through their own representative institutions in order to obtain their free, prior and informed consent before adopting and implementing legislative or administrative measures that may affect them." - Article 19.

"States shall consult and co-operate in good faith with the indigenous peoples concerned through their own representative institutions in order to obtain their free and informed consent prior to the approval of any project affecting their lands or territories and other resources" - Article 32 extract.

* On land ownership rights

"Indigenous peoples have the right to own, use, develop and control the lands, territories and resources that they possess by reason of traditional ownership or other traditional occupation or use, as well as those which they have otherwise acquired." - Article 26 extract.