Christopher Luxon has labelled Labour's Chris Hipkins "ridiculous" for accusing him of insulting his own National Party backbenchers as "no better than a bunch of Air New Zealand middle managers".

"It's not something I would say," Luxon told reporters at Parliament on Wednesday.

Hipkins made the claim during a fiery debate on Tuesday afternoon, telling MPs that Luxon had badmouthed his caucus colleagues to a group of businesspeople in Auckland.

"I'm not sure who should be more offended by that: the National Party backbench or the middle managers at Air New Zealand, who, frankly, deserve a hell of a lot more respect than that," Hipkins said.

Asked for more details on Wednesday, Hipkins said he was told about the exchange by an Auckland businessperson "a couple of years ago" but did not have any proof.

"I'm taking that person at their word," Hipkins said.

Luxon told reporters that the Labour leader was just trying to create a side-show and distraction.

"That's a ridiculous thing from Chris Hipkins," Luxon said.

"He's under pressure because he wants to level nine new taxes on New Zealanders. It's not something I would say."

Luxon said the media should instead be focusing on Labour's proposed capital gains tax and its "unfunded promises".

"I get it. [Hipkins] wants to make the election about me. I want to make this election about taxes and New Zealanders."