Parliament's Speaker of the House has called off an inquiry into the leaking of Simon Bridges expenses.
Trevor Mallard says he believes the culprit responsible for leaking expenses comes from within the National Party.
Mallard called off the inquiry on Friday, saying it was a matter within the National Party therefore parliament did not need to be involved.
The call comes after both Mallard and Bridges received anonymous text messages last week from someone claiming to be responsible.
Bridges told media, "The text made clear to me that it was from the leaker.”
“The text stated that it was in the National caucus, it also made quite clear that this person had a prolonged serious mental illness and serious issues in relation to that."
Bridges says police have confirmed the identity of the person behind the message.
Details of the author have not been released.
Bridges says, "I can say to you I don't know and I don't think I can safely say whether it's a National MP, whether it's another MP, whether it's someone on the staff of National wider."
Bridges dismissed questions over whether the leak saga has revealed cracks within the party or the stability of his leadership.
However, former National MP Claudette Hauiti says it spells troubling times for the Māori leader.
"For some National Party supporters though that's enough for them, to be wary about having a leader that is Māori, and he has talked quite openly about Treaty settlements and about being more connected and having Paula Bennett as his deputy as well too.
“It might be a little bit uncomfortable for the very right of National Party supporters, so yes, he needs to be very careful."
Bridges says he hoped the inquiry would get to the bottom of the leak, to secure the well-being of the person responsible and to uphold parliamentary systems.