The Medical Board of Australia has proposed to suspend the medical registration of voluntary euthanasia advocate Philip Nitschke.

The Australian Health Practitioner Regulation Agency, which provides support to the Medical Board of Australia, launched an investigation into Dr Nitschke following reporting by the ABC.

Dr Nitschke admits he supported Perth man Nigel Brayley in his decision to commit suicide despite knowing he was not terminally ill and was only 45 years old.

Mental health groups Beyond Blue and the Black Dog Institute believe Dr Nitschke had an obligation to recommended psychiatric help to Mr Brayley, but Dr Nitschke says it was not his role to intervene.

In a statement, the Medical Board of Australia says it has contacted Dr Nitschke.

"The South Australian Board of the Medical Board of Australia has proposed to suspend the medical registration of Dr Philip Nitschke," the statement said.

Dr Nitschke said he will respond to the Medical Board soon.

"Of course we'll be challenging that as they seek to make their decisions, and of course our lawyers are working on that now," told the ABC.

The Medical Board says Dr Nitschke will have the opportunity to present his case.

"After hearing from Dr Nitschke, the board will decide whether suspending Dr Nitschke's registration is needed to keep the public safe, pending other inquiries."

Speaking in Melbourne, Dr Nitschke said "the Medical Board, under pressure, has suddenly decided that immediate deregistration seems to be the best option. So that's what they decided to do."

"There's a period of time and it's now determined to be within 48 hours of all the ABC transcripts being produced, the decision will be made.

"I've got 48 hours from when those tapes arrive, my lawyers have got 48 hours to respond. So, it hasn't happened but certainly that's what they are planning."

Dr Nitschke is still registered as a medical practitioner and his registration is up for renewal in September.

The Medical Board of Australia says it "is focused on public safety and managing risk to patients" and has the power to limit a practitioner's registration in some way to keep the public safe while other investigations or processes continue.

It says the board can take "'immediate action as an interim step when it believes there is a serious risk to public health and safety that needs to be managed".

People seeking support and information about suicide can contact Lifeline on 13 11 14.

Do you know more about this story? Email investigations@abc.net.au