Police are investigating after a man allegedly used fake qualifications to work as a doctor at Auckland's Middlemore Hospital.

The man was stood down over concerns about the authenticity of his alleged qualifications. Health officials have lodged a complaint with police, who are now investigating.

Te Whatu Ora Health New Zealand says the person was employed in February and held a clinical research position. The agency said it supported the district health board in referring this matter to police.

However, it is not answering NZME's questions around what reference checks were done on the man, how many patients the person saw, and if patients had been informed.

Health Minister Andrew Little said he was advised of the allegations yesterday and was satisfied with Te Whatu Ora's response.

"I was advised yesterday that a staff member at Middlemore Hospital was stood down last week following concerns raised about his qualifications. I have been advised that an investigation is under way into the actions of this person. I am satisfied at the response of Te Whatu Ora Health NZ to this employment matter," Little said in a statement to RNZ.

Police confirmed a criminal investigation is under way and inquiries are ongoing.

"However as these are still in their very early stages police are unable to comment further at this time," a police spokesperson said.

The Herald understands the person who allegedly used fake documents to get a job at Middlemore Hospital was not seeing patients routinely like a proper clinical doctor and would not have done anything unsupervised.

The patients he would have seen would have been stable outpatients enrolled in a clinical trial.

A staff member at the hospital told the Herald it was strange that he made it through the employment process.

"Doctors have to have super thorough references, etc, that all get called so no idea how he made it through that . . . if you were a doctor working in the main hospital you'd be found out pretty quickly."

Middlemore Hospital is one of the busiest hospitals in the Auckland region, and bore the brunt of Covid-19 and other illnesses causing staff shortages in past months.

The Herald reported in June, a "healthy" 50-year-old women died with a brain bleed after allegedly being told by staff at Middlemore Hospital's emergency department there would be an eight-hour wait before she was examined. The case sparked an urgent review.

Emails leaked to the Herald from a different doctor showed the hospital's emergency department saw more than 420 patients for the second night in a row that week. Normally the department saw around 300 people. The increase saw the hospital shift to code red, which the doctor said basically meant "a level of panic".

In September 2020, the Herald revealed police were called after a member of the public disguised himself in scrubs and snuck into a Wellington Hospital operating theatre during a major surgery. A medical student on placement at the hospital was alleged to have helped him.

The case represented a massive privacy, medical and security breach - it was understood the patient was unconscious on the operating table.

Capital & Coast DHB chief medical officer John Tait confirmed at the time that the breach took place, after a member of the public got into a surgical theatre "under false pretences".

"We have apologised to the patient and family affected, and wish to take this opportunity to apologise again. We take patient privacy and our security responsibilities incredibly seriously, and no breach of this nature is acceptable," said Tait at the time. "We launched an investigation as soon as the breach was discovered. We understand that the actions of a medical student were involved in the breach."

Police had been contacted about the person getting into the surgical theatre, Tait said, and the Office of the Privacy Commissioner advised. "We are now reviewing our security systems and protocols to minimise the risk of such a breach occurring again."

A police spokesperson confirmed at the time that they were told of the incident, "however it was not considered to be a police matter".