A Melbourne GP facing suspension by the Australian Health Practitioner Regulation Agency has vowed to continue helping anti-vax parents sidestep "no jab, no play" laws until he is deregistered.
Dr John Piesse was advised by the regulator on Thursday afternoon that it was proposing to suspend his medical registration. He was given four days to provide a written response in his defence.
The GP, who has previously been reprimanded by the regulator, is unrepentant, saying he has been "deluged" by parents wanting to avoid getting their children immunised.
Dr Piesse, who works from the Natural Healing Centre in Mitcham and the Natural Institute of Integrative Medicine in Hawthorn, said he had seen about 450 children since late 2015 but did not provide a letter of exemption for every one.
"I have tried to help," he said.
He insists he is doing nothing illegal.
When asked if he would continue assisting anti-vax parents, he replied: "I will ... until they basically deregister me ... unless I can be persuaded that what I am doing is wrong.
"This is a matter of principle. You have got a public health policy which is causing harm ..."
Dr Piesse and his colleague, naturopath Nerida James, attended a screening of the controversial anti-vaccination film Vaxxed in Hawthorn this month, where he told participants there were ways in which parents could get vaccination exemptions and he knew of other doctors who were providing them.
"There are a few who are doing it as well, but they will get attacked as well," he said.
"The system cannot tolerate doctors who don't follow the government's line."
It is understood complaints are set to be lodged with the regulator over two other doctors in suburban practices who are also involved in promoting an anti-vaccination message.
Under "no jab, no play" legislation introduced in 2016, childcare services and kindergartens must first obtain evidence that a child is fully immunised for their age, or on a catch-up vaccination program, or is unable to be fully immunised for medical reasons, before enrolling them.
Many parents involved in the anti-vaccination movement fear a link between the measles, mumps and rubella vaccine and autism. Such a link was first suggested in 1998 by UK researcher Andrew Wakefield.
His research, which was based on only 12 children, has since been disproved and retracted.
Victoria's Health Department first raised concerns with the regulator over Dr Piesse after he wrote to the Health Minister in August 2016 to apply for exemptions.
Acting Health Minister Martin Foley said he was concerned the investigation into Dr Piesse was yet to be completed.
"It is deeply disappointing and concerning that after 12 months an investigation into Dr Piesse's practice has not yet been concluded by AHPRA. It's not good enough," he said.
"By failing to vaccinate their children, parents are putting their kids and others in our community at risk of terrible diseases or death.
"Practitioners who peddle ... misinformation about immunisation are a menace and put the health and safety of children at great risk - they must be stopped."
Federal Health Minister Greg Hunt said he was astonished to learn registered doctors would "stoop to the level of supporting the anti-vaccination movement".
"Vaccination saves lives and it protects lives. It's safe, as the Chief Medical Officer and all of the body of research points out, and if it is accurate that there are registered doctors who are advocating an anti-vaccination position then they will have the full force of the authorities come down on them," he said.
"There will be no sympathy, none at all, from the government if the authorities take the strongest possible decisions."
Medical Board of Australia chairman Dr Joanna Flynn, said the regulator could not comment on individuals but that all registered medical practitioners were held to account against the board's code of conduct.
"The board expects registered doctors to practise the profession safely and ethically," she said.