A member of parliamentary staff has been stood down after a historic allegation of assault, Speaker Trevor Mallard says.

A formal complaint was laid with the general manager of Parliamentary Service about the person after Mallard's radio interview this morning.

"I am satisfied that the Parliamentary Service has removed a threat to the safety of women working the parliamentary complex.

"I want to thank the staff member [who laid the complaint] who has come forward .... This is obviously a very traumatic time for that individual, and will also be the case for other individuals, other women, who are involved."

He encouraged anyone who had been assaulted to ring the Safe to Talk line - 0800 044 334 - or contact police or the Parliamentary Service general manager.

"My appeal to the media is to let the process run and take care not to further traumatise either this woman or other women."

He said the person has been "stood down" while the employment investigation was underway.

He said it was up to the woman involved, not himself, to refer the matter to police.

The person voluntarily came forward and was stood down this afternoon, Mallard said.

He was not aware of the allegation, which was an assault of a sexual nature, before the Francis review.

He stood by his comments this morning that the incidents of sexual assault were tantamount to rape.

Asked if parliament was safe, Mallard said: "One can never make an absolute guarantee of that type, and clearly we have a lot of work to do out of the review around attitude."

But he said one of the dangers had now been removed from the premises.

The Speaker, Trevor Mallard. Photo / Mark Mitchell

Mallard said he understood that one person was responsible for the three serious incidents raised in the Francis review.

He said his comments this morning, as well as media coverage, had contributed to re-traumatising victims. "It would have been better if it had not played out that way."

He said a formal complaint was laid with the general manager of Parliamentary Service about the person after his radio interview this morning.

Earlier, Prime Minister Jacinda Ardern called a sudden meeting with Mallard and party leaders after his comments about a possible rapist working in the parliamentary precinct prompted widespread safety concerns.

Yesterday Mallard and independent reviewer Debbie Francis released a review of bullying and harassment at Parliament, which revealed 14 people who said they had been the victim of a sexual assault in the parliamentary workplace.

"Three of the alleged incidents disclosed to me in interviews were in my view extremely serious and some appeared to be part of a multi-year pattern of predatory behaviour," Francis said in the report.

Mallard characterised the three incidents as rape, adding that he believed the perpetrator still worked in Parliament.

The comments prompted National deputy leader Paula Bennett to say that staff had come to her "feeling ill and uncomfortable and nervous," while New Zealand First leader Winston Peters said Mallard's comments were "absolutely repugnant" because they were offered without any evidence.

Safety concerns from parliamentary staff prompted Ardern to call an urgent meeting with Mallard and Leader of the House Chris Hipkins, followed immediately by a meeting between Mallard and all party leaders.

"We were all given assurances by the Speaker that he was taking appropriate steps to make sure that this is a safe place for people to work," Ardern said.

She would not be drawn on what those steps were or whether Mallard's comments were out of line, adding that Mallard would address those issues when he spoke to media this afternoon.

She said the safety concerns that led to the meetings were also shared by Mallard.

"His motivation is still making sure this is a safe place, a place where people are treated with dignity and respect. The report we all saw yesterday has of course shown that, currently, that is not the case, and we have a huge amount of work to do."

She said the decision to lay any police complaints was for any victims, who had spoken to Francis on condition on anonymity.

"The choice of reporting to the police is ultimately for them," Ardern said.

Mallard said this morning that his reading of the Francis report was that the three incidents were the actions of one man who was still working at Parliament.

"Reading the report carefully, I get the sense that the man is still on the premises," he told Morning Report.

"I'm not aware whether they are an MP or staff ... I don't know who it is. If I knew who it is, I would tell the police."

He characterised the alleged incidents as rape.

"We're talking about serious sexual assault. Well that, for me, that's rape."

He hoped that victims were being supported by the proper agencies and would make a complaint to police if they wanted to.

"Each of the chief executives of the different agencies, each of the party leaders, has been encouraging women who have been sexually assaulted, or assaulted in any way, to go to the support agencies who can support them with a complaint to the police."

Bennett said that police should be called in, regardless of whether Mallard knew the identity of the offender.

"Debbie Francis does [know the identity]. She was contracted by [the Speaker]. Something else needs to happen.

"For me, it almost feels like they are harbouring a criminal ... This is not just a bit of inappropriate behaviour. The Speaker is alleging a very serious criminal act. I'm not convinced that everything is being done that should be."

Bennett said she was not necessarily calling on Francis to breach the conditions of her contract and name people to police, but police should at least be called in for advice.

Asked if Parliament was a safe place for women, Bennett said: "It doesn't feel like it today."

Peters said Mallard's comments were lacking evidence and therefore "absolutely repugnant, not correct in any way, shape or form, and we're not going to sit back here and take those sorts of allegations".

"To sheet the evidence home, you've got to have a complainant. Frankly, when you're going to make statements like that, you better know the processes of the law. I'm very unsatisfied with what I've heard."

Peters said the offender was not someone who worked for any political party.

"It's not a parliamentarian and it's not a parliamentary staffer, so all the parties are clear on this matter ... so that leaves just the system itself."

It is unclear what Peters meant by "the system".

He said he would not say what he was basing that on except to say "it's what I know".

Green Party co-leader James Shaw said he was not able to talk about the meeting with Ardern and Mallard.

He said the issue was something that was "incredibly concerning".

"We have to do everything we can to make sure this is a safe place for women to work in."

Justice Minister Andrew Little said allegations that there is a rapist in Parliament were "very serious".

"If that allegation is substantiated, it's right for appropriate action to be taken."

He said for the police to investigate, they would need to have a better knowledge of the information in the Francis report.

"If disclosures were made under conditions, particularly at the behest of the victim of a survivor, then that does change what can happen."

Without knowing what those conditions were, he said he could not say what the appropriate course of action should be.

National MP Judith Collins, who is a former Police Minister, said police did not need a complainant to investigate.

"I would have thought, if there is evidence at that level - so much so that there is a report of three sexual assaults, apparently by one person - that that matter should go to police, if there is any idea about who this person is.

"I think people would like to know. Certainly a lot of the men working here would like to not have themselves being smeared by this."

She did not know who the person was but said she would be surprised if it was an MP.

The Francis review went back as far as 2014, but Mallard said that the complaints could have been about earlier incidents because the review had allowed that.