Napier MP Stuart Nash has apologised to a fellow MP after calling her a "nutter" on live radio.

Speaking on Mike Hosking's Breakfast show on Wednesday morning, the tourism minister referred to Act Party MP Nicole McKee as a "nutter" after discussing her choice to knit in the House of Representatives on Monday.

Nash - who was police minister during the Government's gun buyback - initially doubled down on his comment when asked whether he'd like to apologise to the new Act MP, stating her views are "extremist".

"I know Nicole's views on a number of things, including guns," he said. "I won't say they're dangerous because nobody takes any notice of them."

But after Act called on Prime Minister Jacinda Ardern to "pull Stuart Nash into line", the Napier MP issued an apology.

"I have apologised to Nicole because it was very poor form on my behalf," he told Hawke's Bay Today.

Act leader David Seymour with Nicole McKee (left) and Brooke van Velden. Photo / File

McKee, who has been knitting since she was a child, says there's a time and a place for knitting in the House and during the tributes to the Duke of Edinburgh felt appropriate.

"When I'm preparing for speeches or listening to debates, I know it isn't the right time. But yesterday, as MPs paid tribute to Prince Philip, I thought it was," she said.

McKee was within her rights to knit in the House following a rule change in 2002 allowed knitting in Parliament – just not in a minister's chair.

• Act MP Nicole McKee brings out the knitting needles in Parliament
• ACT demands apology after Stuart Nash calls Nicole McKee 'a nutter'

When asked by Hosking what percentage of the Labour Party knit, Nash said the topic of knitting has never come up.

Act health spokeswoman Brooke van Velden released a statement after the show calling on Prime Minister Jacinda Ardern to "pull Stuart Nash into line" after the incident.

Van Velden said the comments were not the standard the public expects of cabinet ministers, but highlights "why we haven't seen any movement from Labour on mental health".

"If this is what Nash says in public, I can't imagine what he says to his colleagues in private," she said. "Our politicians need to show leadership."

Van Velden said wait times for youth mental health services are on the rise and government officials are "hiding damning reports".

"They can begin by focusing on the serious issues faced by New Zealanders, not by dragging others down."

Asked what she thought of Nash's comment's, McKee referred media to Van Velden's statement.

A spokesperson for Prime Minister Jacinda Ardern said Nash had apologised to Nicole McKee and Ardern considers that the end of the matter.