MP Jami-Lee Ross has released a recording of a phone conversation between himself and National Party leader Simon Bridges discussing a $100,000 donation from Chinese businessman Zhang Yikun.

Several National MPs believe Jami-Lee Ross may have taped them in "leading" and "weird" conversations about Simon Bridges' leadership of the party in recent months.

Two National MPs, who did not wish to named, told Stuff they had strange conversations and phone calls with Ross in recent months, which they now suspect were taped. Both say others in the party have similar worries.

Ross, who resigned from the National Party in spectacular fashion Tuesday but is still an MP, released a secretly-taped phone call on Wednesday between him and National leader Simon Bridges to support his allegation of electoral fraud.

HAGEN HOPKINS/GETTY IMAGES Jami-Lee Ross on Wednesday outside a police station. Several of his former colleagues suspect he taped conversations with them.

The tape, while providing no smoking gun for the electoral fraud allegation, was politically embarrassing for Bridges as it included a frank discussion of the race of his MPs, and a discussion of "culling" some MPs - including lowly-ranked Maureen Pugh, who he called "f..... useless".

Ross and Bridges were close, with then-whip Ross serving as Bridges' "number's man" during the leadership race - calling MPs and securing their votes for him as leader.

One senior MP said Ross approached them in person a few months ago to propose the two strike up a kind of political alliance.

This MP told Ross "no" in "very strong terms" - and said they wouldn't be too upset if the tape did come out.

The senior MP said at the time they were confused by this but now they believe he was attempting to get them to talk about destabilising Bridges' leadership.

Another MP said Ross called them around a month ago to ask what they thought of Bridges' leadership.

"At the time I thought of him as 'Simon's guy' so I was pretty confused about why he was asking me questions about what I thought of him," the MP said.

The MP said this concern was widespread within the party.

"It's natural now that people know he taped Simon everyone is going back through their conversations with him and going 'oh yeah'. Things take on a different hue."

Two more MPs who talked to Stuff said they had never been close enough to Ross to have those kinds of conversations, but the worry was natural for those who had been close.

Ross has made clear that he recorded conversations to "protect" himself, saying he did this after Bridges brought four allegations of harassment to him three weeks ago in a move he saw as an attempt to "push him out" of the party.

However, the conversation he has released of Bridges is from June 25, months before that. Ross said on Thursday he didn't "make a habit" of recording his colleagues, but did record that earlier conversation because he was worried about the legal status of the donation.

"When I felt as though the National Party was attempting to push me out or that the leader of the National Party is asking me to do something that I am uncomfortable doing that's when I've decided that I need to protect myself and ensure that there was voice recordings of our conversations," Ross said.

"I don't regularly record phone conversations. The allegations that were put forward to me [three weeks ago] were so staggering that when I went back for two subsequent meetings with Simon also felt like I needed to protect myself so I recorded those conversations.

Ross has been approached for comment.