A man allegedly used fake qualifications to gain work as a doctor and treat dozens of patients in the respiratory unit at one of New Zealand’s top hospitals, Kiwi health officials say.

The man, who had reportedly also posed as a medical student for two years, began working at Auckland’s Middlemore Hospital in February in a clinical research role and regularly reviewed patients under supervision, according to the hospital.

However, his employment was terminated on 1 August after concerns were raised about his clinical abilities, eventually leading to questions about whether he had ever officially attended medical school.

In a statement on Friday, the hospital – one of Auckland’s biggest – admitted it was now believed the man had falsified his registration with the New Zealand Medical Council, the country’s equivalent of AHPRA.

It apologised to patients and said it was now in the process of contacting all of those who had come under the man’s care.

However, it was not believed that any patient had been harmed, claimed Dr Andrew Connolly, chief medical office of the local health board called Te Whatu Ora Counties Manukau.

“We have reviewed the care of every patient who was seen by this person,” Dr Connolly said.

“This includes investigations, treatment plans and the dispensing of any medications during the time the person was at Middlemore Hospital.”

“We are now contacting all patients seen by this person. A thorough investigation of the clinical care provided by the person has told us that there has been no compromise to any patient’s care.”

Radio NZ reported last week the man had posed as an experienced researcher but co-workers became suspicious after noticing large parts of his work were “not up to standard”.

They said his colleagues initially noticed he was falling short on the clinical aspects of his work but tried to help, before eventually raising the alarm with management.

All up, the man saw 70-80 patients in the unit over almost six months, the broadcaster said.

Local media outlet Stuff said it was not the first foray into medicine for the man, reporting on Thursday he had previously “forged a student ID card” to attend classes at the University of Auckland’s medical school between 2010 and 2012.

At the time, a spokesperson from the university’s medical school said the man participated in the second and third year of the six-year medical course, despite never being officially enrolled.

He was alleged to have dissected cadavers, managing to fly under the radar thanks to the course’s large class sizes, the spokesperson said.

In an interview at the time, the university’s medical dean Professor John Fraser said the man had applied for entry into the medical program but had been unsuccessful.

“Ultimately the presence of this person was detected when an assignment was submitted that did not match any name on the class list,” Professor Fraser said.

“This individual is not a student and is not on any class list. This person has not been given any confidential or restricted training material and has not, to our knowledge, ever been able to examine any patients or received confidential patient information.”

According to one report, the man held a Bachelor of Science undergraduate degree from the University of Sydney.

NZ police said a criminal investigation was now underway.