Covid-19 Response Minister Chris Hipkins has labelled the handing out of unofficial Covid-19 vaccine exemptions as unethical behaviour.

Dr Jonie Girouard, who runs a weight loss clinic, was filmed using a hidden camera as she spoke to people in her waiting room. "You're here because you're not crazy about being vaccinated. Great, okay you are in the right spot," she said. "I mean really this is horrible, horrible medicine."

The doctor told a Newshub reporter, posing as wanting an exemption so he could work on mandated building sites, how to do "spiel" to potential employers. "They don't know what they're doing, you got to coach them."

She told patients one of her certificates had been used for international travel. "I have had someone be able to fly to Australia last week on one, so I mean we have had some success stories reported back to us," she was filmed as saying.

Exemptions must be approved by the Ministry of Health, and cannot be issued by health professionals.

Hipkins told Morning Report he was sure there would be investigations by the ministry and the GPs' professional body.

He said information the doctor was handing out was wrong.

Hipkins said it was "very unethical behaviour - it almost certainly doesn't meet the standards that the GP profession set for themselves".

Medical Association chair Dr Alistair Humphrey said police should investigate.

Humphrey said he had been told police were aware of the report.

There was case law that doctors could be successfully prosecuted for fraud if they were found to have issued false certificates, he said.

Investigations by the College of GPs or the Health and Disability Commissioner would any follow any police inquiry, he said.

Humphrey said everyone knew a GP could not issue an exemption. "Employers should be aware that any of this kind of note is not the appropriate way of going about it."

The GP was filmed saying she was not vaccinated, which Humphrey that would be a breach of the mandate for health practitioners.

He said she was not a member of the Medical Association.

The Health and Disability Commissioner has received 11 complaints about vaccination exemptions provided by health professionals but could not say if Girouard was the subject of a complaint due to privacy rules, it said.