National has bowed to Maori Party wishes and agreed to support the highly contentious United Nations Declaration on the Rights of Indigenous Peoples despite the previous Labour Government issuing dire warnings that the document is fundamentally incompatible with New Zealand's constitutional and legal systems.

New Zealand's support for the declaration was conveyed in a speech early today by Maori Affairs Minister Pita Sharples at the United Nations in New York.

The declaration recognises the rights of indigenous peoples to self-determination, being able to maintain their own languages, being able to protect their natural and cultural heritage and manage their own affairs.

Dr Sharples, one of the Maori Party's co-leaders, said this morning's announcement restored the mana and moral authority of Maori to speak in international forums on justice, rights and peace matters.

But National appears to have given its backing to the declaration on condition a proviso is attached saying that progressing Maori rights occurs within New Zealand's "current legal and constitutional frameworks".

When the declaration was finally placed in front of the UN General Assembly in 2007 after years of preparation, the previous Government expressed with "genuine regret and disappointment" that New Zealand could not support it even though it was non-binding.

New Zealand was one of only four countries to vote against the declaration.

Explaining that vote, New Zealand's then permanent representative to the UN, diplomat Rosemary Banks, said one article in the document gave indigenous peoples the right "to own use, develop or control lands and territories they have traditionally owned, occupied or used".

She said the entire country was potentially caught within the scope of that article. "The article appears to require recognition of rights to lands now lawfully owned by other citizens, both indigenous and non-indigenous ...

"Furthermore, this article implies indigenous peoples have rights that others do not."

New Zealand's "explanation" also saw major problems with the declaration's provisions on redress and compensation for indigenous peoples. The declaration also implied that indigenous peoples had a right of veto over Parliament and management of national resources.

The Maori Party has been pressing National to back the declaration. But the Government has proceeded cautiously, being well aware of the potential fish-hooks in it and worried about a public backlash.

Negotiations have been going on for months, with the Prime Minister last year reluctant to put a time-frame on when those talks would reach a resolution.

John Key referred to the negotiations as being a work in progress, saying it was a matter of "crossing all the t's and dotting all the i's".

National's concerns appear to have been dealt with by the attachment of the rider to New Zealand's statement of support. This proviso reaffirms "the legal and constitutional frameworks that underpin New Zealand's legal system" and notes that those existing frameworks define "the bounds of New Zealand's engagement with the declaration".

Dr Sharples said the Labour Government's position had called into question Labour's commitment to Crown-Maori relations and undermined New Zealand's credibility on human rights issues.