Hundreds of iwi members may be left thousands of dollars out of pocket after New Zealand First changed its mind over supporting Treaty settlement legislation.
All political parties had agreed to a special sitting of Parliament on Friday to allow five bills for Taranaki, Manawatu and Far North iwi to pass with support of all of Parliament.
Over 400 iwi had made travel and accommodation arrangements to come to Parliament to celebrate the long-awaited passing of the legislation.
Treaty Negotiations Minister Chris Finlayson says New Zealand First had supported it - but changed their minds today.
He says the behaviour is appalling.
"Not only does this postpone the final settlement of long-standing historical grievances which have been negotiated over many years, but delays tens of millions of dollars of commercial and financial redress from entering the regions," Mr Finlayson said.
"This bizarre u-turn delays the benefit settlements bring to iwi, communities, regional New Zealand and the country as a whole."
Maori Party co-leader Marama Fox said: "I'm absolutely appalled that New Zealand First can hold this Parliament to ransom like that, having previously agreed two weeks ago, yesterday saying they don't have a problem. And today, on the whim of their leader, they've thrown all those plans out the window."
This is all the government's making, it tried to rush these bills through via the business committee- Winston Peters
She says iwi have had 30 years of pain up to this point and this just adds to that.
But NZ First leader Winston Peters says there's no reason to delay the settlement bills, calling today's outburst as "hysterical behaviour".
"These bills can all go through on time, but it will require members to be here and not on holiday," Mr Peters said in a statement.
"If these two ministers think standing up for the rights of parliamentarians is 'appalling behaviour' it explains why the National Party has become so arrogant.
"This is all the government's making, it tried to rush these bills through via the business committee, when it should have kept to the democratic, standard procedure," says Mr Peters.
New Zealand First's opposition means all MPs would have to be in Parliament for the bill to pass.
The special agreement means that if there's unanimous support, that's not the case.