Jacinda Ardern has apologised to the complainants who made allegations against a Labour Party staffer, admitting harm was caused by the process of an investigation by the party.
"I offer an unequivocal apology for them," the Prime Minister and Labour leader told media today.
It comes after Labour Party president Nigel Haworth resigned today over the handling of a sexual assault allegation levelled at a party staffer.
"I do want to offer an apology on behalf of the Labour Party to those complainants in this case who have gone through a process that I believe has caused some harm," Ms Ardern said.
She said the party and Mr Haworth stood by his statement on Monday that said the "serious allegation of sexual assault ... was not provided to the president and acting general secretary at a meeting in the Wellington Central Library or subsequently to the Labour Party Investigation Panel".
"Despite that, I've seen correspondence that has clearly shown to me that despite [the party's] best intentions that this process has caused harm and that is not acceptable," Ms Ardern said.
"Despite the plans of the party to conduct a process that they thought would bring a resolution - it brought harm."
"The process itself, the party was never adequately equipped to deal with we just didn't have the expertise the experience to deal with sensitive matters."
Ms Ardern said she raised concerns with Mr Haworth and he offered his resignation.
In the wake of the allegation, a group of party members known as Me Too Labour called on Mr Haworth to resign on Monday, sending an open letter to Ms Ardern.
The group told 1 NEWS so far 212 people have signed the letter, with 101 of those identifying themselves as Labour Party members.
Today, the group released a statement saying it was a "step towards acknowledging that Labour has failed these survivors".
However, it urged Labour to make "internal changes necessary to ensure that a process like this never occurs again".
"We are still calling on Nigel Haworth to apologise to the survivors for the handling of this process under his leadership."
During debate in the House today, National Deputy Leader Paula Bennett said the complainants who had spoken to her felt "hunted and scared".
"Hardly a victim-led response," she said.