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.

Police are investigating a complaint made by Jami-Lee Ross about National Party leader Simon Bridges' handling of an alleged $100,000 donation, the Electoral Commission says.

An Electoral Commission spokeswoman said it had been contacted by police in response to Ross's complaint and it was providing advice as required.

"We are unable to comment further while those investigations continue," the spokeswoman said.

Police would not comment.

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Last Monday after Bridges pointed the finger at Ross for leaking his travel expenses, Ross went public with claims Bridges had breached electoral law in his handling of an alleged $100,000 donation from wealthy businessmen Yikun Zhang and Colin Shijia Zheng.

Ross alleges the payment was split into smaller donations, so it could remain anonymous.

KEVIN STENT/STUFF Jami-Lee Ross leaves the Wellington Police Station after he made a formal complaint about National Party leader Simon Bridges.

Zhang and Zheng are not being accused of any wrongdoing.

Bridges strongly denies the allegation and invited Ross to take evidence to police.

So that's exactly what Ross did. On Wednesday he took to police a recording of a conversation between him and Bridges in which they discuss the donation.

After visiting Wellington Central Police Station Ross released a tape to media from June 25 in which Ross and Bridges discuss the donation and how to handle it, but there is no smoking gun.

ROSS GIBLIN/STUFF National Party Leader Simon Bridges denies donation fraud allegations made by Jami-Lee Ross.

Zheng was mentioned in the recording as a possible candidate for the National Party.

On Tuesday National Party President Peter Goodfellow said Zheng had entered the National Party's Candidate College for the 2020 election. The Candidate College acts as a kind of boot camp for potential National Party candidates, but it does not guarantee selection.

Last Wednesday police confirmed that a complaint had been received regarding the disclosure of political donations under the Electoral Act.

Police said at the time the information supplied would be assessed by detective senior sergeant at police national headquarters to determine what further steps may be required from a police perspective.

Police would not put a timeframe on how long this would take.

"We can say that this will be progressed as quickly as the information presented to us allows," a written statement said at the time.

Penalties for failure to comply with the Electoral Act range from a fine of $40,000 at the lower end, to a maximum of two years in prison and a fine of up to $100,000.

The Electoral Commission is only aware of one case resulting in a conviction - two low-profile candidates from unregistered parties were fined $200 each after the 2008 general election for failing to file expense donation returns.

The only active prosecution involves People's Party secretary Anil Sharma, who is facing five charges of failing to file donations made to his party exceeding the sum of $30,000.

Last week Ross said he would resign from the National Party and contest a by-election in his seat of Botany as an independent.

He was expelled from the National Party after women came forward to media to allege they had either been bullied by him or had consensual but threatening sexual relationships with him. Ross disputes aspects of the story.

At the start of October Ross took leave from Parliament to deal with personal health issues.

Ross was taken into mental health care late on Saturday night but had since been released.

Last Thursday a source told Stuff Goodfellow helped broker a "peace agreement" that included a confidentiality clause between Jami-Lee Ross and a woman who felt threatened by him.

The agreement was signed before Bridges became leader of the party and promoted Ross to the front bench. It is unclear if Bridges was aware of the incident.

Bridges had since said the National Party would review its workplace practices following the Ross saga.

It would seek independent advice on whether its current systems for dealing with such matters when complainants came forward were up to scratch.