New Zealand’s parliament has erupted into fiery debate, personal attacks and a haka over a controversial bill that proposes to radically alter the way New Zealand’s treaty between Māori and the crown is interpreted.

The treaty principles bill was tabled by the libertarian Act party – a minor partner in New Zealand’s coalition government – and passed its first reading on Thursday, amid scathing speeches and disruptions.

A vote on the bill was momentarily suspended, when opposition parties and people in the public gallery joined in a haka (Māori dance or challenge), led by the Te Pāti Māori MP Hana-Rawhiti Maipi-Clarke, who proceeded to rip up a copy of the bill.

The bill seeks to remove a set of well-established principles that has flowed from New Zealand’s founding document, the treaty of Waitangi – an agreement signed in 1840 between more than 500 Māori chiefs and the crown, and which is instrumental in upholding Māori rights.

The principles of the treaty have been developed over 50 years by courts, tribunals and successive governments to help guide the relationship between Māori and ruling authorities and iron out differences in interpretations over the English and Māori texts of the original treaty. Many principles have been developed and continue to evolve, but the most recognised are broadly defined as participation, partnership, protection, and redress.

They have been used in efforts to revitalise the Māori language, including making it an official language, and were used to establish a Māori health authority to reverse poor health outcomes for Māori, which the coalition government dismantled this year.

Critics of the bill say Act’s proposal undermines the treaty and its principles, which they believe threaten Māori rights and promote anti-Māori rhetoric.

There has been significant public backlash to the bill, with thousands of people joining a nine-day hīkoi (protest march) this week. Starting at the tip of the North Island, participants are expected to arrive at parliament on Tuesday.

More than 40 king’s counsel lawyers also wrote an open letter to the prime minister, Christopher Luxon, and the attorney general, Judith Collins, urging them to abandon the bill.

Speaking in the house, Act’s leader, David Seymour, said the principles “afford Māori different rights from other New Zealanders … The purpose of this bill is break this parliament’s 49 years of silence to define the principles in law so it is crystal clear what the treaty means to modern New Zealanders”.

Seymour’s address was met with groans and exclamations of disapproval from opposition parties, prompting the speaker of the house to repeatedly ask for the “barrage” of rebuttals to stop.

Labour’s Willie Jackson followed Seymour with a withering rebuke of the bill and its architect. “Shame, shame, shame, on you David Seymour,” he said. “I said some time ago that [Seymour] was the most dangerous politician in New Zealand, and that has come to pass.

“The principles are clear – they are about partnership, equity, active protection and redress – why does this offend the minister so much? … This bill will undermine Māori rights but still David Seymour persists with this disgusting piece of legislation.”

Jackson ended his speech by calling Seymour a liar, and was forced to leave the house when he refused to retract his statement.

The Te Pāti Māori co-leader Rawiri Waititi delivered a similarly impassioned address, likening the Act party to the “KKK with a swipecard to the Beehive [New Zealand’s parliament]” and calling them “complicit in the euthanising of the treaty of Waitangi”.

Opposition parties called on coalition MPs to vote down the bill. “My question to MPs is: are you here to hold on to power at any cost, or are you here to do the right thing?” said Chlöe Swarbrick, the Green party co-leader.

“Are you here to listen to your conscience, or are you here to give it all up on one of the most significant votes in this house in our lifetimes? Because if you wear the mask for a little while, it becomes your face.”

The introduction of the bill formed part of Act’s coalition agreement with National – the major centre-right party. National and the third coalition partner, New Zealand First, have ruled out supporting the bill beyond the first reading and select committee process, meaning it is likely doomed to fail.

The justice committee will hear submissions on the bill, which is expected to take six months, after which it will return to parliament for a second reading.