National MP Maurice Williamson is offering a full apology for offensive comments he made at an Auckland business conference last week.

His performance as MC has been described as sexist and misogynistic by some of those who were at the event.

Mr Williamson has issued a written statement offering an unreserved apology.

He said it was never his intent to upset any delegates.

Mr Williamson said he overstepped the line on the night and did cause offence.

The Pakuranga MP's MC spot at the New Zealand Esri Users Conference gala dinner at SkyCity last Tuesday had people of "both sexes were removing themselves from the room", one woman said.

The crowd was "pretty surprised", said the woman, who wished to remain anonymous.

"There was a lot of women at the conference. My major problem with [his comments] was that it was like a really embarrassing stag do, something you'd pull out at a stag do when there weren't any women there and certainly not clients.

"That was my disappointment. Not only from a female perspective, I thought it was very inappropriate, but I'm a business relationship manager and I had a lot of clients in that room. If they thought that was a representation of the industry I would be pretty embarrassed by that."

The woman said she had made a formal complaint to organisers about Mr Williamson's comments, which she described as being "blokey", "old boys kind of jokes", that "harked back to the 1980s".

He also included jokes about his staff, she said, which she felt put them "in the same boat".

"The [theme of the] conference dinner was comics, supervillains and super heroes, and he made a comment that he'd asked his staff to go out and look for costumes for him and then put up these sort of really inappropriate pictures of, for want of a better word, porn stars wearing Superman, Batman and Spider-man costumes - or lack of, to be honest.

"It was misogynistic and sexist ... I know the Parliamentary staff work very hard, and I'm sure they wouldn't be very happy about being represented that way."

Mr Williamson, who tweeted a picture of himself dressed as the 1980s TV character the Greatest American Hero outside the conference, also made a joke about a scantily clad Wonder Woman, and played an audio clip from a US radio show entitled 'Atta Girl Knee Pads', which targets women and gay men.

The fake advert includes the line: "Atta Girl Knee Pads fit right in your purse, so you can take them anywhere - perfect for a Friday night date or that important job interview. Ask your boyfriend to get you some."

In reference to gay men, it said: "Your bum may be sore, but you won't have a bum knee."

The attendee said after the Wonder Woman joke "it just went downhill from there".

"At that point both sexes were removing themselves from the room. Some of us were just sitting there going, 'you've got to be joking'. There were people that left the conference dinner and came back in once he'd finished."

But it was the fake radio advert that was "really the low point," she said.

"Everybody at that point just went, 'oh wow, you've got to be joking me'. It was really disappointing."

Multiple requests for comment to Mr Williamson and his offices have not been returned.

The conference hosted a women in business breakfast the following morning. It was aimed at mentoring women into senior management position, which was like "going from the ridiculous to the sublime", she said.

"The previous night we were sitting there basically being [told] the size of your boobs and getting on your knees is how you get ahead, and it was just such a dichotomy."

Americans at the conference were "shocked" that the speaker was a sitting MP, she said.

Eagle Technology, which hosted the conference refused to comment today, with Duane Eagle hanging up when contacted.

"I've said we've got no comment to make on that matter," he said, before putting the phone down.

Eagle Technology sent an email to all guests apologising for Mr Williamson's presentation.

"Corallie Eagle, Duane Eagle and all of the Eagle Technology staff offer our sincere apologies to all who attended the NZEUC Conference Gala Dinner last Tuesday night, for the content and references made by the MC, Maurice Williamson," it said.

It went on to say that Mr Williamson had asked the company to convey his apologies also.

"His intention was certainly not to offend, but rather to entertain and he regrets the offence caused."

John Key: Williamson "over-stepped the mark"

Prime Minister John Key has not spoken with his under-fire backbench MP Maurice Williamson since his "sexist" conference speech, but thinks he has "over-stepped the mark".

The gaffes are "probably not the threshold for leaving Parliament", Mr Key told reporters today.

While Mr Key has not spoken to Mr Williamson personally, he said officials from his office have today.

"I suspect he's had a chance to reflect on it and probably acknowledges that he has over-stepped the mark. Hopefully [we] wouldn't see a repeat of that," the Prime Minister said.

"Everybody knows that Maurice is a bit flamboyant, a bit sort of out there sometimes.

"My understanding is that he wasn't there in his capacity as an MP. That doesn't absolve him of the things he may have said or done."

Mr Key said he wasn't aware of what was specifically said.

"I am simply speculating and I think it was clearly over the line," he said.

"He wouldn't be the first Member of Parliament that's said a few things they probably regret. In the end, it's probably not the threshold for leaving parliament."

He doubted that he would be disciplined, given that he is a backbench MP who was not at the conference in his capacity as an MP.

Sue Moroney, Labour's spokeswoman for Women's Affairs, said Prime Minister John Key and Minister for Women Louise Upston should be seeking more details about what caused the apology.

"If the organiser of the event feels embarrassed enough about those comments to have apologised for them, then both the Prime Minister and Minister for Women ought to have a talk with Maurice Williamson and find out exactly what happened.

"If there are allegations of misogyny...clearly Maurice Williamson was asked to MC the event because he is a Member of Parliament, then he is there representing his party. They do need to find out what he said, and address any issues that arise from that."

Ms Moroney said she believed earlier controversy over Mr Key's pulling of a waitress's pony-tail would "make it very difficult for him to raise this issue with MPs like Maurice Williamson".

A spokeswoman for Mr Key said his office had spoken to Mr Williamson about the event.

Mr Key will be holding a media stand-up - already scheduled and not in response to the allegations - later today and is likely to comment further then.

 Maurice Williamson's history in politics

Mr Williamson has been the MP for Pakuranga since 1987.

He is also a former Minister of Research, Science and Technology, Communications, Statistics, Information Technology, Transport, Local Government and Broadcasting.

Mr Williamson resigned as a minister last May following revelations he contacted a top-ranking police officer after businessman Donghau Liu was arrested on domestic violence charges.

He also made international headlines and became an icon for his "big gay rainbow" speech at the final reading of the same-sex marriage bill.