Mana Party leader Hone Harawira was thrown out of Parliament today when he tried to pledge allegiance to the Treaty of Waitangi during a swearing-in ceremony.

When asked to read the affirmation, Mr Harawira instead read from a page in Maori, and Speaker Lockwood Smith asked him to leave the House.

During the confrontation about 60 supporters of Mr Harawira in Parliament's public gallery broke into a waiata. They continued to sing after Mr Harawira left, despite repeated calls from Dr Smith for the group to show respect for the House.

After Mr Harawira left, Dr Smith said the MP was advised the law required the oath of affirmation to be taken in a set way.

The oath could have been made in Maori, but the specific wording still had to be followed.

"As Speaker I did not make this decision lightly, there has been a tendency in recent times to abuse our law."

The oath was not just a custom but spelled out in law, Dr Smith said.

"Hone Harawira was advised of the need to comply with the law and he chose not to."

Dr Smith said Mr Harawira could try again the next day Parliament sat, which is on August 2.

Labour MP Trevor Mallard, who has been before the courts for disrupting Parliament, asked for Mr Harawira to be given another chance to take the oath today, as did Green Party co-leader Russel Norman. Those requests were met with loud objection from the National Party.

Following his expulsion, Mr Harawira was greeted on Parliament's forecourt by more than 100 supporters performing haka and waiata.

Addressing them, Mr Harawira said Dr Smith had denied him the opportunity to raise the treaty as part of his affirmation.

"It's a signal of exactly where we are and where we go as a people."

Mr Harawira repeated the oath he had begun to read in Parliament, translating it into English.

"I, Hone Pani Tamati Waka Nene Harawira, swear that I will be faithful and pledge true allegiance to the Treaty of Waitangi," he said.

"That I will be honest and forthright in my efforts to advance the rights of the people of Tai Tokerau, that I will do my upmost to help all Maori people become full and valid citizens of this land, and that I will do whatever I can to reduce the inequalities in this country."

Speaking to reporters afterwards, Mr Harawira said there was scope for the oath to proceed, but Dr Smith had chosen not to allow it to happen.

"The formal affirmation was the last part of the statement but I never got a chance to say it."

His statement was about affirming his allegiance to the Treaty, the people of Te Tai Tokerau, Maori generally and those in society who have been marginalised.

"I wanted to affirm first of all my allegiance to the Treaty of Waitangi. It's more important to me than the oath to Parliament."

There was no reason he should not have been allowed to continue with his statement, he said.

"That's something that perhaps he has to think about, particularly given that he has allowed numerous others to affirm in different ways in the past - rules for some and rules for others."

Mr Harawira was not opposed to the affirmation and he would swear it as required on August 2.

"I managed to finish the oath that I wanted to finish today, so it's just the last little bit that needs to be completed now."

Asked about losing out on his salary until he was sworn in, Mr Harawira said he did not put himself forward for the money.

"I do this because the people demand change, because there's a need for an independent voice in the house, and not just a translation service for other parties."

Mr Harawira said he had been sworn in his way at the last two elections, "so I don't know what the fuss is this time".

"I suppose it's because the whole world's watching. Back then I was one of what, 120 MPs, I suppose."