A doctor acting as a psychiatrist in Waikato has pulled off the "most complex identity fraud" the health board has ever seen, Health Minister Jonathan Coleman says.
The man allegedly used legitimate documents and referees belonging to another man with the same name, Stuff.co.nz reported.
He used a qualified doctor's genuine medical certificate in India, and the man's former colleagues as referees to vouch for his work, it was reported.
The real psychiatrist works in Naperville, Illinois, Stuff.co.nz said.
The alleged fraudster was vetted by the Medical Council of New Zealand and granted a vocational registration, Stuff.co.nz said.
Council chairman Andrew Connolly told the website: "The Medical Council's concern is that the doctor may have obtained registration he was not entitled too.
"We believe the documents we have are legitimate documents. The question we will need to answer is ... was he entitled to use these documents; if not, how did he obtain them and what steps do we need to take as a council to prevent anyone else attempting the same thing."
An inspection into the Waikato District Health Board's mental health service was announced this week following the arrest of the man working as a psychiatrist.
Health Minister Jonathan Coleman said the DHB mental health services would be formally inspected under Section 99 of the Mental Health Act.
A man working as a psychiatrist at Waikato DHB appeared in Hamilton District Court on Saturday on a possible identity fraud charge.
Mr Coleman told Newstalk ZB the inspection would find if the DHB was "up to scratch".
"They will be held to account if things are found to be deficient," he said.
"We've got to know the exact details. From what we're hearing it's the most complex identity fraud that they've ever had."
This is the third incident at the Waikato DHB this year -- former patient Nicky Stevens was found dead in March after leaving the mental health centre and two people scaled a wall to escape just a month later.
Mr Coleman said further action -- including a wider-range enquiry -- might be taken after the inspection if it was warranted.
He said the inspection was also about holding the Medical Council to account.
"They've had three serious incidents this year, each one of those would be unfortunate, when you put them together we've got to have an inspection to give people assurance that the services are at the quality that the public expect and deserve.
"Things can go wrong in mental health ... in the end we've got to get that assurance. I'm not drawing any conclusions in a preliminary way."
The man in question has been remanded in custody to re-appear in the Hamilton District Court on Monday.