The former registered nurse has made end-of-life issues a signature of her decade in the ACT Legislative Assembly and used a letter to The Canberra Times on Wednesday to criticise Dr Nitschke's dealings with a depressed 45-year-old man who was not terminally ill and later killed himself.

Ms Porter said the case of Perth man Nigel Brayley proved Dr Nitschke was "far more interested in his own self-aggrandisement than he is in promoting rational debate".

Last week, the South Australian board of the Medical Board of Australia moved to suspend the long-time campaigner and activist's medical registration over the case.

"I've always thought he was a zealot," Ms Porter said in an interview. "Once people get into entrenched positions, whatever they might be, it's very difficult to have a logical conversation where people listen to each other."

She said Dr Nitschke had promoted a negative perception of voluntary euthanasia and assisted suicide and that some overseas experts questioned his methods and campaigning style.

Ms Porter completed a three-week study tour to Switzerland, the Netherlands and Belgium last year to meet with patients, lawmakers, doctors and ethicists to discuss end-of-life issues.

Commonwealth law passed in 1996 restricts the ACT and Northern Territory from legalising euthanasia.

The Andrews Bill, named for Social Services Minister Kevin Andrews, was a private members' bill passed to overturn attempts by Northern Territory to legalise voluntary euthanasia.

Ms Porter said Dr Nitschke's long-running campaign limited informed debate about end-of-life options such as palliative care and informed planning.

"He comes along and he has his plastic bags and his [barbiturate] Nembutal and its about people paying attention to Dr Nitschke and him being the saviour," she said. "When I talked to people overseas who know him, who are pro-euthanasia and work in the field, they told me about experiences they have had with him that have not been positive."

Dr Nitschke said Ms Porter had repeatedly criticised his campaign and political activities over the years.

"The broader debate is much bigger than her blinkered view that it's all about simply passing a piece of legislation which will allow terminally ill people under set, very specific circumstances to get lawful help to die," he said. "To try and argue that, when people do get embroiled in the much bigger debate about where the borders of these important moral and ethical issues lie, is somehow or other damaging to the cause, or damaging to the euthanasia debate, I think shows a very limited understanding of the broader issue."

Dr Nitschke confirmed his lawyers had begun the process of lodging an appeal against his de-registration on Tuesday.