A man who sought treatment from Australian vaccination campaigner Chris Savage was later admitted to Hawke's Bay Hospital.

Health authorities were alerted to a self-styled "therapist" operating in Hawke's Bay after a man he treated was admitted to hospital.

Hawke's Bay District Health Board issued a warning on Wednesday about Chris Savage, a prominent Australian anti-vaccine activist who also describes himself on social media as an "oxygen therapist to detox efficiently".

The DHB said it had been told Savage was offering medical treatments in the Napier area, and advised the public not to follow any medical or treatment advice he gave, because he was not registered with the New Zealand Medical Council.

The board said it had referred the matter to police and the Ministry of Health.

READ MORE: Public warned against taking Christopher Savage's medical advice

The DHB would not comment further on Thursday, and would not say how Savage came to its attention.

Police also declined to comment.

It is understood, however, that his presence in Hawke's Bay came to light after a patient who had sought treatment from him was subsequently admitted to hospital.

Australian media reported last month that Savage, a former Queensland police officer, had returned to Australia from Bali after local authorities there began investigating him over allegations that he was offering medical treatments for autism and other conditions.

News Corp reported that Indonesian authorities said they would investigate Savage for allegedly violating local health laws if he returned to the country.

Savage, who Australian authorities said had no registered medical training, had been in Bali for several months allegedly providing "services" he said he was not allowed to offer in Australia, according to News Corp.

Those services included intravenous infusions of magnesium and a chemical called DMSO, or dimethyl sulfoxide. He advertised the infusions and said he could treat problems that Western medicine was unable to fix.

Savage told News Corp he was not personally doing the procedures but that a "specialist", whom he was not prepared to identify, was doing them.

​Savage has been approached for comment.