John Banks has been having a miserable life as an MP and it's going to get worse.

On Thursday, when police released their file on the donations to his 2010 Auckland mayoral campaign, he didn't show up at parliament.

Banks isn't a quitter, but the ACT leader must be wondering whether it's worth staying on as MP for Epsom.

He has been targeted by opposition MPs for months over his denials that he knew internet millionaire Kim Dotcom gave him $50,000 for his campaign, and the election return that listed them as anonymous.

Until now, they've had to rely on Dotcom's reported comments that Banks solicited the donation and wanted it kept quiet.

That situation has changed. The police file lays out a series of sworn affidavits that present conclusive evidence Banks knew where the money came from.

They also prove he misled the media.

The file reveals that in February this year Dotcom's lawyer phoned Banks to ask for his help in getting Dotcom an extra mattress for his Mt Eden prison cell.

In his statement to police, lawyer Greg Tower says Banks told him he wanted to publicly support Kim but that might backfire on Kim if the donations became known.

In May, Banks was asked by reporters whether he knew Dotcom made donations to his campaign fund.

"No, I didn't know," Banks replied.

That was captured by TV cameras and the clip was shown on Thursday night.

There is more in the file that proves Banks knew about the donations, including testimony that Dotcom sought assurances that his cheques had been cleared, and Banks' confirmation that they had been.

The MP is now in a position of having to defend the indefensible.

He can claim, as he always has, that he didn't break the law and police decided not to prosecute him.

But that doesn't excuse his denial to the media that he knew about the donations, and when he does show up in parliament he will again be asked to explain why he said "No, I didn't know".

Labour MPs came into the debating chamber on Thursday armed with copies of the police file, ready to confront Prime Minister John Key with fresh demands for Banks' dismissal as a government minister.

Key wasn't there, and Economic Development Minister Steven Joyce was in the hot seat.

All he could say was that Banks had assured Key's chief of staff that he hadn't broken the law.

Key later rejected Labour's demands, saying nothing had changed and the attacks on Banks were "politically motivated".

Of course the attacks are politically motivated, and something has changed.

Key's defence that he still has confidence in Banks because he "didn't break the law" looks increasingly lame against the conclusion, revealed in the file, that the election return was false but the MP couldn't be prosecuted because the time limit for that had expired.

And proof that Banks misled the media makes it increasingly difficult for Key to continue to assert that "the only test" of the MP's fitness to hold ministerial warrants is a legal one.

This isn't going to go away.

Labour MPs sniff blood, and when parliament sits next week they're going to be very interested in why Banks' statement to the police wasn't included in the file, and what is in it.

Police say the disclosures that were made were based on consent of those asked, including Banks.

The New Zealand Herald reports that when Banks was interviewed by detectives for three hours, he insisted it be kept private.

His press secretary says "Mr Banks is not responsible for what the police have released".

Opposition MPs are going to want a better answer than that.

NZ Newswire

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