National Party leader Simon Bridges says the Serious Fraud Office (SFO) investigation into the New Zealand First Foundation adds weight to calls for Winston Peters to be stood down.
The opposition has also been pushing for the New Zealand First leader and deputy prime minister to step down amid questions about whether his party had anything to do with photos of journalists ending up on a blog linked to WhaleOil.
Bridges told Morning Report that putting everything together, it was not a good look for New Zealand First and that Prime Minister Jacinda Ardern had adopted a "hear no evil, see no evil" position on the matter.
"We've been asking him to stand down before we knew about an investigation by the SFO announced yesterday," he said.
"The matter that we originally called for action over was the photograph of journalists, what I consider to be unethical behaviour. I think there's also the Provincial Growth Fund allegations and a raft of things there."
"Jacinda Ardern needs to stand her deputy prime minister down. I think the prime reason today for that is that unethical behaviour, a complete inability and lack of desire to answer basic questions about things that, at the start of this year, the prime minister was quiet clear were bad and dirty politics, and yet now she has a "hear no evil, see no evil' position on."
RNZ revealed the New Zealand First Foundation had received donations from entities connected with some of the country's wealthiest business people in amounts just under the threshold at which the donors' names would normally be made public.
The Electoral Commission said it believed the Foundation had received donations which should have been treated as party donations and had referred the matter to police to investigate. The police then referred it to the Serious Fraud Office.
Peters has repeatedly denied any wrongdoing and when asked if he would step down as a minister he said: "Why would I do that...if the Electoral Commission didn't speak to me why would you ask that question?"
Last week Peters also tweeted: "NZF has no interest in following Mr Espiner or any other journalists. The very reverse applies. No private investigators have been engaged to follow Mr Espiner or anyone else. A supporter thought it odd seeing ex-president Lester Grey with Mr Espiner so took a photo. Simple."
But Bridges rejected a statement from the New Zealand First caucus that it had nothing to do with taking photographs of RNZ journalist Guyon Espiner and Stuff reporter Matt Shand this month. The reporters had been meeting former NZ First president Lester Gray.
"That's not what Winston Peters first said and it beggars belief the fact you've got in one case a very well-known journalist, another not, with photographs of them ending up on a political blog. I think those circumstances mean New Zealand First was clearly involved in it. It was planned... Clearly because Winston Peters won't say anything about the details of it, there's more to this."
Regarding political donations reform, Bridges said he was open to change but it wasn't a matter he was focused on. Currently, a person can make three anonymous donations of $15,000 per year to a party.
Bridges would not be drawn on Serious Fraud Office charges relating to two $100,000 donations made to his own party.
Four people face charges over the donations in June 2017 and June 2018. The SFO alleges a "fraudulent trick or device" was used to break up the 2018 donation into sums less than $15,000, which were then transferred into the bank accounts of eight different people, before being paid into a National Party electorate account.
It also said that happened "in circumstances where the identity of the donor was not disclosed in National's annual return".