Labour MP Gaurav Sharma is doubling down on his claim a colleague misused taxpayers' money despite the Parliamentary Service determining no spending rules were broken.
The MP for Hamilton West launched an extraordinary attack on his own party last week, claiming rampant bullying and gaslighting within Parliament.
Sharma accused the Parliamentary Service, Labour's whips and the Prime Minister's office of facilitating the poor culture, in a piece published by the New Zealand Herald.
Jacinda Ardern rejected the accusations, instead saying there is a dispute over employment issues within Sharma's office.
Sharma then hit back with a lengthy 2600-word statement posted on his Facebook page.
In the statement, Sharma claimed an unnamed Labour MP and a parliamentary staff member had misused taxpayers' money.
He alleged the misspending was "hushed" and never looked into.
Sharma said he raised the matter with the Parliamentary Service last August "as someone who took an oath to uphold and protect the interests of this country".
Parliamentary Service chief executive Rafael Gonzalez-Montero confirmed the complaint was looked into last year.
He said the money in question was spent on travel for a Wellington-based staff member, who was visiting an MP's electorate office "for the purpose of team building and assisting the wider team."
"This is normal practice for many members when establishing a new team which has staff dispersed in different regions."
Parliamentary Service determined the expenditure was for parliamentary business and therefore not in breach of the rules, Gonzalez-Montero said.
But Sharma told RNZ "they [Parliamentary Service] definitely did not investigate it."
He also questioned why the Parliamentary Service informed the Labour Party about his complaint.
Sharma claimed he was bullied as a direct result.
"I was told by then Junior Whip Duncan Webb that what I did was wrong and I should be ashamed of myself...
"I was then told by Duncan Webb that an accusation like this could mean that the government could get into trouble, lose the election etc and such issues needed to be contained rather than discussed freely."
Webb told RNZ the allegations were "unfounded and not accepted" but did not want to comment further.
A spokesperson for the Labour Party said it disputed the allegations made by Sharma.
Gonzalez-Montero told RNZ the Parliamentary Service works closely with all parties in Parliament.