National Party leader Judith Collins says she won't attend Waitangi next year if she is again denied the same speaking rights as the Prime Minister.
Meanwhile, Jacinda Ardern says she'd like all political parties to be represented, but the way that was done was up to the Waitangi National Trust.
Collins spoke out in February about not being afforded the same opportunity to speak during the politicians' pōwhiri at Waitangi.
Prime Minister Ardern has been allowed to speak from the mahau (porch), however Collins and Green Party co-leader Marama Davidson were denied the same right despite sitting next to her.
Plans for them to speak after the ceremony were scotched after everybody left.
The speaking issue was gently raised by National's speaker, deputy leader Shane Reti of Ngāpuhi and Ngāti Hine descent, during his whaikōrero. He asked them to please reconsider it, saying it saddened them that the women could not speak.
Traditionally the roles in pōwhiri (welcoming ceremonies) are seen as equal, with women in front for the karanga, men in front for whaikōrero, and side-by-side for waiata at the end. Afterwards the floor was open to all to speak.
However tikanga (custom) about who could speak and when, particularly when politics was involved, varied marae to marae, iwi to iwi, and had long been challenged by wahine Māori.
Collins spoke out in media afterwards, calling for a change to tikanga at Waitangi, which caused strong reactions from all sides including Davidson, who said Collins had ignored the work of wahine Māori to further the discussion around tikanga and lacked the "cultural expertise" to comment.
Collins however was given a commitment at the time by Ngāti Hine elder, Te Waihoroi Shortland, that things would change next year. He said it would have been "more engaging" had Collins spoken.
The Waitangi National Trust is currently considering the matter, but if she is again not able to speak on the paepae, Collins said she would not attend.
"I think the time has come to call this out. It is not something I will be accepting again. I do not think any political leader, certainly the Prime Minister or leader of the opposition should have to apologise for their gender.
"And in addition, the mana whenua women, who have been prevented themselves speaking ... is unacceptable. We have to change this."
Ardern said it hadn't been an issue in earlier years with male leaders, but ultimately the decision was for the Waitangi National Trust.
"Of course I would support all political parties speaking on the day but the way that is done is for the Waitangi National Trust."
She said she'd never felt unable to speak or engage on an issue at Waitangi personally.
Māori Development Minister Willie Jackson said his personal view was that tikanga should evolve and all women should be able to speak on the paepae.
"But we shouldn't change just because Judith Collins and Shane Reti make a complaint. Judith knows very little about tikanga, this is about National wanting to get one up on us."
Treaty Negotiations Minister Andrew Little, who is Pākehā but has drawn praise for his whaikōrero at Waitangi in te reo, said decisions around tikanga were best left to Māori.
"Parliament now is as diverse as you can imagine, we've had plenty of women Prime Minister, ministers, leaders that need to be accommodated, but how Māori evolve tikanga is in their hands - it is not for Pākehā to tell Māori what to do.
"We are all part of discussions of what the 21st century Aotearoa New Zealand looks like but tikanga is the preserve of Māori. They control it, decide what happens."