Euthanasia campaigner Philip Nitschke says his suspension by the medical board was a “dirty little midnight assassination”.

Euthanasia campaigner Philip Nitschke has vowed to fight his suspension by the Medical Board of Australia, calling it a “dirty little midnight assassination” aimed at silencing him.

The board on Wednesday night used its emergency powers to suspend Dr Nitschke after ruling that he posed “a serious risk to the health and safety of the public” following his links to a West Australian man who had sought advice about how to take his own life.

But Dr Nitschke said he had very little to do with Nigel Brayley, 45, who died in May after attending an Exit International workshop in Perth in February.

“To suggest that my passing acquaintance with Brayley implies a doctor-patient relationship, and an implied duty of care, makes a mockery of good medical practice,” he told reporters on Thursday.

Dr Nitschke said the medical board told him his view that people have a right to choose to take their own life was incompatible with his responsibility as a doctor.

The suspension, which came into effect at midnight – two hours after Dr Nitschke was informed – prevents him from practising anywhere in Australia and is an interim measure pending the outcome of an inquiry.

Dr Nitschke said he did not need a medical certificate to continue his work with Exit International, but would fight the suspension so others could not use it to discredit him and his message.

“I will continue to provide end-of-life choices workshops to the growing number of elderly Australians who want this information.”

Mr Brayley, 45, died after taking euthanasia drug Nembutal.

Police were investigating his possible involvement in the February 2011 death of his wife Lina, 37, after she fell from the top of a quarry while taking photographs.

Dr Nitschke said Mr Brayley was a lucid adult of sound mind, but was not his patient.

“Nigel had sought to acquire his drugs before I even met him,” he said.

“There was nothing that I could or did say to Nigel that would have made him change his mind.”

The medical board had conducted a trial by media, which went against the rule of law and Australian democracy, he argued, and sought to “carry out a dirty little assassination aimed at silencing me and stifling discussion on this important social topic.”

“It beggars belief that a government board can act purely because it does not agree with the beliefs of its citizens.”

But Jeff Kennett, chairman of beyondblue and a supporter of euthanasia for the terminally ill, welcomed the suspension, saying Dr Nitschke had damaged his own cause.

Beyondblue and other organisations, as well as various governments, were working to reduce suicide rates, Mr Kennett said.

Some 2535 people took their lives in 2012, which was double the national road toll.

“I think he wanted a debate to try and legitimise the right of individuals to take their lives whenever they wished,” he said.

“We cannot allow the debate to start that it’s alright for a 16-year-old, or a 45-year-old, simply because they’re having an off day, to attempt to take their own life. It is not acceptable.”

* Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14 or the Suicide Call Back Service on 1300 659 467.