United Future leader Peter Dunne says a private prosecution being brought against him by a former accountant is "nonsense".
Wellington man Graham McCready filed papers today at the Wellington District Court and sent documents to Mr Dunne.
Mr Dunne said he received the documents today, but had not had a chance to get a legal opinion on them.
He said his initial reaction was that the charges were "simply nonsense".
Mr Dunne is the third politician Mr McCready has targeted for prosecution, alongside ACT leader John Banks and Labour MP Trevor Mallard.
Mr McCready has accused Mr Dunne of fraud by receiving $3846.10 between April 30 and June 1 as a fortnightly instalment of his $100,000 payment as a leader of a registered political party.
During this time the party had determined there were insufficient numbers to declare United Future had 500 members, and Speaker David Carter had made no determination that Mr Dunne could keep the money in the meantime, Mr McCready said.
"Mr Dunne finds himself in the same position as a welfare beneficiary who has had a substantial change of circumstances, takes no steps to alert WINZ of the change and continues to receive the money when he has no 'colour of right' to receive it.
"Nor did he take any steps to return the money or hold it in trust."
Mr McCready also alleged Mr Dunne disclosed the existence of the Ketteridge Report into the GCSB inquiry; disclosed he had a copy of the report; and that he disclosed in whole or part its contents to Fairfax reporter Andrea Vance.
Mr McCready had also requested 86 emails sent between Mr Dunne and Ms Vance under the Official Information Act.
Mr McCready is bringing a private prosecution against Mr Banks for knowingly receiving political donations from internet mogul Kim Dotcom and SkyCity that were recorded as anonymous.
Mr Banks has pleaded not guilty to the charge.
In 2009 Mr McCready took assault proceedings against then Labour Cabinet Minister Trevor Mallard after the MP's scrap with National MP Tau Henare in the lobby of Parliament.
Mr Mallard pleaded guilty to fighting in public, and paid a $500 fine.