Prime Minister Jacinda Ardern has apologised to ACT leader David Seymour for calling him an "arrogant prick" in Parliament.
Speaker Adrian Rurawhe said he will review Parliament's Hansard records.
The moment occurred just after Ardern answered a question from Seymour about how she handles mistakes.
After answering, Ardern sits down and Speaker Adrian Rurawhe begins to call the next question. Ardern's microphone remains live and she can be heard saying: "Such an arrogant prick".
Following Parliament's Question, Seymour spoke to media.
"Some days I am a useless Maori, others days I am an arrogant prick," he said. "The apology we are really looking for is for New Zealanders worried about rising prices and ram raids."
"Jacinda Ardern text me and said, I apologise, it's not something I should have said and she said, as my mum would say, if you don't have anything nice to say, don't say it.
"I agree with the sentiment and it is all good as far as I am concerned. I just said, thank you and I hope you have a very merry Christmas. At the end of the day, it's not the end of the world."
Ministers leaving the House were also taken by surprise by Ardern's comment.
Kiri Allan said the comment would be "an inappropriate characterisation".
After being told the Prime Minister had used the remark, Allan said: "Oh is that right? I am sure she wouldn't use that language."
Allan was then told Ardern had apologised for it.
"Oh that is good that we remain collegial despite of all of our various different feelings for each other in heated moments."
She said she had called people an "arrogant prick" on the odd occasion.
"I am not sure what you're referring to," said Dr David Clark upon being asked whether "arrogant prick" is appropriate language to use in the House.
"I have no idea what you're referring to," said Chris Hipkins. "I haven't seen it so don't want to comment. It is difficult to comment on it without having seen it. But if she's apologised, then yes, that's the right thing to do."
Hipkins then got flustered when asked if Seymour was an "arrogant prick". He refused to answer and walked off.
Damien O'Connor said the comment might be appropriate for some politicians, while Stuart Nash also wouldn't comment on whether Seymour was an "arrogant prick".
"He's lots of things," said Carmel Sepuloni. "Those are not the words I'd use."
After being told Ardern had used those words, she just repeated herself.
National's Nicola Willis called it "poor form".
"It's not language that I would use. I don't think he's arrogant. I don't think he's a prick," said National's Chris Bishop.
ACT's deputy leader Brooke van Velden said Seymour is a "great guy" and the Prime Minister's comment was unparliamentary.
"She has done the right thing by apologising," she said.
ACT Party MP Simon Court was also asked if Seymour is an "arrogant prick".
"Absolutely not, David's lovely. He's great to work for," he replied.
Asked if Seymour had told him to say that, Court shook his head.