A doctor found guilty of professional misconduct used threatening language saying that people would pay a "bloody price" after negative findings against him by the Medical Council.
Gardaí are investigating the issue after the Medical Council passed the communication it received from Dr Omar Hassan.
The council told the High Court today it received the correspondence in March, after Dr Hassan was found guilty of professional misconduct and poor professional performance.
JP McDowell for the council, told President of the High Court Mr Justice Peter Kelly, that the correspondence was "sinister" and not acceptable and that it had been referred to gardaí.
The court heard Dr Hassan wrote to the council saying that he "felt extremely and unfairly negatively portrayed by some media", in coverage he claimed had been invited by the council.
He also said that reasonable explanations did not work and do not work "so me and my family will take things into our own hands in the future as a local culture of a fair revenge may extend down to generations".
The communication said that what had taken place "will be fully paid for at an extremely bloody price for the people involved worldwide as far it can gets".
The development came during a hearing to deal with Dr Hassan's appeal against the recommendation of the Medical Council, that he be struck off the register, for professional misconduct and poor professional performance, following an inquiry last January.
Dr Hassan, who qualified in Sudan, insisted that he had not used any threatening language.
High Court correspondence
Separately, Dr Hassan told the court he did not author an email to a registrar of the High Court on 11 July saying he would not continue with his High Court appeal.
That email said there would be "a grave response from me and my family side in relation to these events outside the court and not necessarily in Ireland."
Mr Justice Kelly said he regarded the email to the courts service computer as extremely serious.
Dr Hassan denied he had authored it, saying he knew nothing about it.
Mr Justice Kelly remarked that it was difficult to see how one email, out of a chain of other emails Dr Hassan had sent to the courts service, was not his.
During the hearing, Dr Hassan declined to handle a copy of the email in question, given to him today during proceedings by a solicitor for the Council, saying he was concerned that it could contain anthrax.
Mr Justice Kelly then invited Dr Hassan to take his copy of the email to read.
When asked again if he had sent it he replied: "No I didn't".
Dr Hassan told the court he had contacted around 20 firms of solicitors for his appeal but most had declined to represent him.
He also said he was unaware of the recommendation that had been made by the council that he be struck off.
Mr Justice Kelly told him to "stop the nonsense" and come to terms with the situation.
Dr Hassan told the court he believed there was a conspiracy against him since he had been employed in Ireland as a doctor.
He also said that no patient had complained about him, or had suffered and that the complaint to the council had been an administrative one.
He also said he had found discrepancies on the Medical Council transcripts of the inquiry into his conduct.
Mr Justice Kelly said that the allegations of a conspiracy had not been made by Dr Hassan in his grounding affidavit for his appeal.
He said there could be no further time wasting, given the matter had been adjourned on a number of occasions to assist Dr Hassan in securing legal representation.
He said that if Dr Hassan could not find a lawyer to represent him, he would have to represent himself at the appeal hearing.
Mr Justice Kelly set the appeal against the Medical Council decision for hearing on 18 October.
It is expected to last up to two days.
