Read the full report into Simon Bridges' leaked expenses

The report into who leaked Simon Bridges' expenses has been released.

PricewaterhouseCoopers (PwC) conducted a "forensic examination" of every National MP's electronic devices in an attempt to identify the culprit.

Mr Bridges' expense documents were emailed to all National MPs on August 7 - but were not due to be made public until August 15.

On August 13 Newshub political editor Tova O'Brien revealed she had been leaked the documents early, which showed Mr Bridges spent more than $100,000 on travel and accommodation over the course of three months while on his national roadshow.

The following day Mr Bridges told media that Speaker Trevor Mallard would look into the matter, and later on that same day called for an independent inquiry into the leak.

While the Speaker began and later cancelled a QC-led inquiry into the leak, he quietly pushed on with his own investigation.

Mr Bridges also commissioned his own inquiry from PwC. That inquiry is now complete and the report can be read below.

Much of the investigation revolved around a text sent to Mr Bridges, the Speaker and O'Brien on August 16, in which the anonymous sender (claiming to be a National MP) confessed to the leak and asked for the inquiry to be called off for the benefit of their mental health.

The report has found that the text message sender was probably - but not definitively - Jami-Lee Ross, who Mr Bridges has already claimed was behind the leak.

It reveals that Mr Ross was in contact with a Radio New Zealand reporter as well as O'Brien. He called that reporter 25 minutes before the anonymous text was sent to Mr Bridges, the Speaker and O'Brien on August 16.

In other evidence that would seem to implicate Mr Ross, the report found that he called a senior police officer in the early afternoon of August 19. Later that afternoon the Deputy Police Commissioner told Mr Bridges that police had identified and spoken with the text message sender.

On August 23 Mr Ross called the RNZ reporter four times between 10:39am and 3:42pm. At 6am the following day, RNZ revealed the content of the text as well as other information that had been sent the previous week to Mr Bridges, the Speaker and O'Brien.

On August 24 Mr Ross called the senior police officer five times between 7:19am and 2:20pm. That same day the Speaker announced he had called off the inquiry, saying it was a matter for the National Party to deal with internally.

The report says the inquiry ruled out every National MP as being the text message sender - with the sole exception of Mr Ross.

While the report points to Mr Ross as the probable leaker, it is not conclusive. The summary says it has not found who leaked the expenses or sent the August 16 text "with certainty". It says the evidence points to Mr Ross and he "may therefore be the text message sender", but the finding isn't definite.