Middlemore Hospital is apologising to patients seen by a man pretending to be a doctor and contacting each one.
The person began working as a doctor at Middlemore in February. Photo: RNZ / Cole Eastham-Farrelly
Police are investigating concerns the man who saw patients used fake documentation to get the job.
Te Whatu Ora Counties Manukau chief medical officer Andrew Connolly said management were "deeply sorry" for the mistake and were contacting every patient.
"We have reviewed the care of every patient who was seen by this person. This includes investigations, treatment plans and the dispensing of any medications during the time the person was at Middlemore Hospital," Dr Connolly said.
The person reviewed patients under supervision, he said.
He started work in February and was stood down on 1 August, when concerns were raised about whether he had registration as a doctor.
He was removed from his role as soon as Te Whatu Ora Counties Manukau was notified of concerns about his New Zealand Medical Council registration status.
His employment was concluded at Te Whatu Ora Counties Manukau yesterday and a complaint was filed with police the same day.
Police have refused to comment while the investigation was in its early stages.
Andrew Little Photo: RNZ / Angus Dreaver
Minister of Health Andrew Little was made aware of the situation on Wednesday.
"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 the hospital was reviewing its vetting processes.
He said he would expect the most robust vetting processes to be in place when people were being recruited into the health system.