The Maori Party have failed to ask the hard questions on water rights and are losing credibility as advocates for their people, says Labour's Maori Affairs Spokesperson Parekura Horomia.

"The Maori Party has not sought the assurances that are necessary from the Government to protect Maori interests in water," said Parekura Horomia.

"They have simply dumped the responsibility for this on Iwi leaders and are failing to play the leadership role that Maori expect of them."

Labour MPs questioned the Minister of Maori Affairs in Parliament today about what steps he had taken to advocate for the interests of Maori in terms of the sale of state-owned assets.

"All Pita Sharples seems to have done is set up a meeting between the Iwi Leaders Group and the Government. He hasn't taken into account the fact that some Iwi are not represented in this group and he has failed to fulfil his duty of care to represent the broader interests of Maori.

The Maori Affairs Minister also failed to provide any advice to the Finance Minister about whether or not the transfer of 49% shareholding interests in state assets would contravene Te Tiriti o Waitangi.

"This admission will surprise Maori given the insertion of a Treaty clause in the Mixed Ownership Model legislation - the stark reality is that this clause may not mean anything of substance for Maori.

"The Maori Party has sat back and simply accepted the assurances given by the Government to the Iwi Leaders Group without being able to tell us what those assurances actually were.

"There is so much at stake here in terms of the important issues raised by Maori about water and the sale of SOEs. The Maori Party are not taking it seriously enough. They have become irrelevant," said Parekura Horomia.