Trevor Mallard has reportedly called off the inquiry into the leaking of Simon Bridges' expenses.

The Speaker has ruled it is a National Party matter and therefore not something Parliament needs to be involved in.

Bridges told a media conference this morning he wanted the investigation continued.

He said police had identified the person who sent him a "dark and concerning" text message claiming to be the leaker of his expenses.

Bridges said he had been "very worried" about the health of the person, who police have spoken to.

The National leader said he received the "dark and concerning" text message on Thursday and it was sent also to Parliament's Speaker Trevor Mallard and a media organisation.

"The text made clear to me that it was from the leaker ... [and that] the leaker was in the National caucus," Bridges told media this morning.

"It also made quite clear that this person had a long and serious mental health issue.

"It was my very clear view there would be significant harm to them if the investigation proceeded. It was a dark and concerning text message.

"I was very worried about it. I spoke to senior colleagues and then replied, saying my utmost concern was for the welfare of the person. Later that day I received expert advice on how to proceed.

"On Friday I informed the police with my clear concern being for the mental health and wellbeing of the individual.

"On Sunday evening police contacted me. They knew and had worked out the identity of the person concerned. They made clear the person was getting the help they needed."

Bridges said police had not told him the person's identity and he understood why this was the case.

Police have confirmed they spoke to the person.

"Police assessed the information supplied as a mental health issue requiring an immediate response," police said in a statement.

"The information provided by the National Party did not identify the individual, however their identity was established through subsequent police enquiries.

"Steps were taken as they are for any matter reported to police where there are immediate concerns for the welfare of an individual."

The National Party was advised that Police would not disclose the individual's identity for privacy reasons.

Police said they had dealt with the matter "entirely from a mental health perspective".

The texter had claimed to be inside the National Party and had leaked Bridges' expenses to punish him for being arrogant.

Bridges said he has not questioned members of his caucus about whether they sent the text.

Bridges says he believed he has the support of his colleagues and his main concern was for the wellbeing of the person who sent the text.