National's deputy leader Paula Bennett says if Winston Peters had any involvement in covert photographs of journalists meeting a source, he is not fit to be deputy prime minister.
Bennett said ministers must uphold the highest ethical standards, and accused Jacinda Ardern of choosing a "see no evil, hear no evil" approach.
Photos of journalists, including RNZ's Guyon Espiner, meeting with a former New Zealand First party president surfaced on a political blog last week.
After initially saying "we took the photos", Peters said supporters of the party took the photos.
Speaking to RNZ's Morning Report today, Ardern kept her distance from the whole affair, saying none of it was a matter for her.
"Indeed, I'm the Prime Minister, I run the government. I do not run three separate parties, so I don't think it's unfair or unreasonable to say that these are matters for New Zealand First, not for me," Ardern said.
But Bennett said the prime minister needed to be asking Peters some very serious questions.
"I do not believe that if what we're seeing is true he can stay in the role as deputy prime minister," Bennett said.
"Instead of asking the questions and perhaps getting answers that would mean she would have to act she is choosing to simply avoid.
"I think she's running scared that he may pull the plug and I don't think they're ready for an early election," she said.
Bennett dismissed Ardern's justification that this applies to Peters with his party leader, not ministerial, hat on.
"I would agree with perhaps the foreign minister ... but he also holds a warrant as deputy prime minister. I've held that warrant.
"If she was in China like she'd planned to go, he would be the acting prime minister. Are these the ethical standards that she believes is fit to be running this country?
"This feels threatening, it feels like it's a threat to all of you, you know how dare you go out there and have confidential sources, we will track you down and we will find you, is what is Winston Peters and New Zealand First seems to be saying," she said.
Bennett was asked about the parallels between this, and activity outlined in the 2014 book Dirty Politics, by investigative journalist Nicky Hager.
It detailed close links between the Whaleoil blog, political advisor Simon Lusk, and National MPs running smear campaigns against political opponents.
The Whaleoil website closed in 2019 in the wake of its parent company going bust, defamation cases and its controversial founder Cameron Slater suffering a stroke.
The BFD website is registered to Andrea Parkes, who has a Whale Oil email address.
But Bennett distanced National from these players.
"John Key stood up, cut all ties. We have nothing to do with people like Simon Lusk and Cameron Slater and I know that, and it hasn't been for many, many years.
"I mean you see Simon Lusk in Parliament buildings going to visit New Zealand First. You hear stories about him being on retainer and actually being paid by someone else to actually do some of the dirty work for New Zealand First," Bennett said.
Lusk told RNZ that he does not comment on who his clients are.
New Zealand First has not responded to questions from RNZ about whether the party is working with Lusk.