The Maori Party says it pulled its support for legislation on the Canterbury Regional Council because it was worried about the transfer of power to unelected officials.
But the National Party still had sufficient support from ACT and United Future to pass the Environment Canterbury Bill under urgency on Wednesday night, replacing the 14 democratically elected councillors with a panel of commissioners.
The National Government on Tuesday appointed the panel after a series of complaints and a highly critical report of the regional council and its management of water issues by former National Cabinet minister Wyatt Creech.
The Maori Party says it got the legislation at short notice, became more concerned as the debate progressed and changed its vote on the third reading. It is also worried about the impact on the rights and interests of local iwi.
The party says it acted in good faith, informing Environment Minister Nick Smith of its intentions just before the final vote.
Dr Smith says he was surprised and disappointed and says the decision is unhelpful to the relationship between the parties.
Maori Party whip Te Ururoa Flavell says the support agreement with the Government has not been breached.