House Speaker Trevor Mallard has announced a member of the parliamentary service staff has been stood down following an "historic allegation of assault".
Mallard said the person was stood down on Wednesday afternoon and confirmed that the assault was of a "sexual nature".
"I want to encourage anyone who has been assaulted to contact the Safe to Talk hotline 0800 044 334, the police or the general manager of the parliamentary service."
- Sexual assault, bullying claims revealed in Parliament
- MPs accused of treating staff like servants in bullying review
- Paula Bennett demands clarification from Speaker Trevor Mallard on rapist comments
Mallard thanked the staff member who came forward. He said it would be "a very traumatic time for that individual and will also be the case for other individuals - other women - who are involved".
"Because the matter is now under investigation, as opposed to being part of a review, it's not appropriate to go into further detail."
Mallard's announcement followed a meeting of political party leaders on Wednesday where they discussed the report into bullying and harassment in Parliament released on Tuesday.
The review, launched in November 2018 and carried out by independent external reviewer Debbie Francis, came back with 85 recommendations, and revealed sexual harassment and assault allegations.
It revealed 50 people reported unwanted touching and 54 people reported unwanted sexual advances. There were 14 reports of sexual assault - 11 made by current staff members.
Mallard told The AM Show on Wednesday morning he was surprised about the revelations of a "serial sex offender" in Parliament, and told RNZ sexual assault cited in Francis' report could constitute rape.
When asked on Wednesday afternoon if he stood by his statement that sexual assault is tantamount to rape, Mallard replied: "Yes."
The report did not identify the accused offenders, which Mallard said was integral to the review, but he did acknowledge that he knew who the offender was, who's been stood down.
"The person is stood down because that is the process that is taken while an employment investigation proceeds. It was not my role to refer it to the police - that was the role of the woman involved."
National deputy leader Paula Bennett had earlier on Wednesday called for Mallard to clarify his comments about a rapist in Parliament and said police should become involved.
Police said they could not confirm or discuss any matters which may have been raised with them as a result of the review process, "given our obligations to individuals who may wish to contact us".
"It almost feels like they are harbouring a criminal," she said. "There are a whole lot of people in this building looking for answers."
She said she sent a note out to staff, some of who she described as feeling "ill", "uncomfortable" and "nervous" after the comments, saying they will be looked after if they decide to come forward.
Prime Minister Jacinda Ardern said on Wednesday she had been given assurances from the Speaker that he would be making sure Parliament is a safe place to work.
"We have to ensure victims have all the support they need but everything needs to be decided by them - the choice of reporting to the police is ultimately for them."
Deputy Prime Minister Winston Peters earlier confirmed that the offender was not an MP but he also said it was not a parliamentary staffer.
"It is not a parliamentarian and it is not a parliamentary staffer - that's number one - all the parties are clear on this matter," he said, when asked about Mallard's comments on Wednesday morning.
"You just can't go out and have an allegation where everybody's now under scrutiny when none of them should have been."
When asked what his assurance was based on, Peters said: "It's based on going and finding out, because I wasn't prepared to hear what I heard this morning."
The review followed allegations of harassment and bullying by former National MP Jami-Lee Ross, as well as accusations against National MP Maggie Barry, and Labour MP Meka Whaitiri who was sacked as a minister last year.
Barry said on Wednesday she had been "reading the report with interest and hearing with horror the Speaker on Morning Report this morning about rapes, and so forth".
"It is at a higher level than what I had thought - the level of abuse."
She said part of the worry from MPs' point of view was that "we're cocooned a little bit from what other staff and other parts of the building are going through".
"To me, those are very worrying elements that are coming through, and I hope the Speaker and everyone within the precinct - once we get our head around the 85 recommendations are all about and how it will change the way we work here - that we should move with speed."
Whaitiri has denied bullying accusations made against her. Earlier this month she said: "From the time that the allegations were made, up until today, I've always refuted them.
The review also revealed harassment based on sexual orientation, with respondents complaining about "constant sniggering and joking about gays".