The National Party has launched an internal investigation into who leaked the travel expenses of leader Simon Bridges.
PricewaterhouseCoopers and Simpson Grierson will lead the investigation, and it will be funded by the National Leader's Office.
The move comes after Speaker Trevor Mallard cancelled a parliamentary inquiry into the leak, saying that the evidence indicated it was a matter for the National Party.
- 'Please tell me' who leaked my expenses - Simon Bridges
- Trevor Mallard calls off inquiry into Simon Bridges' expenses leak
- Simon Bridges' leaker sends anonymous text pleading for end to inquiry
That message came in the form of a text message from the leaker, which was made public.
The text - sent to Mr Bridges, Mr Mallard and Newshub - asked for the inquiry to be abandoned, citing ongoing mental health issues.
The leaker's text provided three specific details of closed-door National Party caucus meetings, with the author saying "I am in your caucus" and "I can prove this".
Despite those claims, Mr Bridges is unconvinced the leaker is a member of his own party.
It's not clear whether the outcome of National's internal investigation will be made public.