Dr Nitschke said he believes Dr Pat Gibney, of Townsville, is a significant danger to the public and unfit to practise medicine after he sent the missive at 12.46am on Monday.

‘‘Dear Phillip,’’ the email reads, ‘‘Please do the world a favour - Take a loaded 12 Ga [gauge shotgun] and put it in your mouth, then shoe [sic] us the courage of your convictions - PULL THE TRIGGER!’’

The email is signed ‘‘Kind Regards, Dr. Pat Gibney, Aitkenvale, Q.’’

Dr Nitschke said he has complained to police and the Queensland Medical Board because he was ‘‘disturbed and concerned’’ about the content of the email. He believes he has had no prior contact with Dr Gibney.

Dr Nitschke’s formal complaint to the medical board, seen by Fairfax Media, states that: ‘‘In light of the violence promoted by Dr Gibney I am concerned for both my own safety and for that of my family and for the Queensland-based staff members of my organisation Exit International.

‘‘As this was an unsolicited, uninvited email, I consider Dr Gibney a person who fails basic ethical and moral standards expected by the community of doctors.

‘‘As a health practitioner Dr Gibney should be aware of the damage that gunshot to the mouth can cause, and the trauma which would befall anyone who should find a person after they have committed this action.’’

Dr Nitschke writes that ‘‘as a doctor, it beggars belief that Dr Gibney would promote an act that brings with it such injuries’’.

‘‘I consider Dr Gibney to represent a significant and immediate danger to the public, given his promotion of violence as evidence in this email. He is unfit to hold medical registration in Australia or elsewhere.’’

Dr Nitschke is the subject of a Medical Board of Australia investigation. In July the board said it had suspended Dr Nitschke’s registration to ‘‘keep the public safe’’ while investigations into his activities are carried out.

This followed reports that Perth man Nigel Brayley, who was being investigated over his wife's death, had communicated with Dr Nitschke before taking his own life in May.

Mr Brayley, 45, who had possibly been suffering depression, reportedly attended a workshop run by Dr Nitschke’s organisation Exit International in February.

The Australian Medical Association, beyondblue and Dying with Dignity led widespread criticism of Dr Nitschke’s work, with some parents claiming their adult children had committed suicide after accessing Exit International information.

But on Sunday, the international ethicist Peter Singer spoke out against Dr Nitschke’s suspension, saying he believed people without a terminal illness could make a rational decision to die.

‘‘I think suicide can be rational in the absence of terminal illness and I think I could find you dozens or hundreds of philosophers who would think that ... I think if you know you are going to spend the next 20 years in prison, suicide is a rational option – not for everybody, but for some people,’’ Professor Singer said.

The Aitkenvale Family Health Centre website states that Dr Gibney has been working as a general practitioner in Townsville for more than 30 years, with an interest in skin surgery, pain management, family medicine and psychological problems including addiction.

In an email to Fairfax Media, Dr Gibney said he had written to Dr Nitschke and apologised to him ''for my ill-tempered outburst which was provoked firstly by my belief the modern palliative care has progressed sufficiently that euthanasia is unnecessary and therefore is contrary to the primary dictum of medicine 'Primum non Nocere' [first do no harm].''

Dr Gibney said he believed that ''the presentation of suicide as a reasonable option feeds into the huge tragic epidemic that is current in this country especially among our Aboriginals. I counsel many parents and relatives of the victims and it is heartbreaking.

''The mention of a shotgun in no way represents an obsession with such instruments nor a threat to Dr Nitschke – it is simply a popular implement of suicide among count[r]y males.''

Dr Gibney said after he sent his initial email to several newspapers as well as Dr Nitschke, he had asked them not to publish it, ''but it looks like Dr Nitschke is determined to publicise it for his own purposes!''

For help or information call Suicide Helpline Victoria on 1300 651 251 or Lifeline on 131 114, or visit beyondblue.org.au.