Mr Justice Moriarty told the tribunal he was "not amused" by comments about his conduct in letters passed between legal teams and read out at the inquiry yesterday.
These "less-than-ideal" letters concerned Mr Denis O'Brien's non-appearance at the tribunal and included claims from the legal team of the former Esat Digifone chairman that the tribunal was biased against its client.
Mr Justice Moriarty said it was the first time in his career as a judge that allegations of being guilty of bias had been directed towards him. "I do not want this tribunal to degenerate into any form of unseemly or guerrilla warfare", he warned.
He was not a "thin-skinned person" and did not wish to take an egotistical stance on the matter. However, he demanded an end to this "type or tenor" of correspondence.
"I'm not amused by these observations by letter which I consider to be entirely unwarranted and unjustified," he said. "I would ask that experienced and senior practitioners reflect, in the course of the preparation of letters, on duties owed to institutions of the State, such as this tribunal."
The judge said he would continue to provide objective and fair appraisal of all facts that emerged in the course of the inquiry. "If it were in any way otherwise I should not be here as chairman and I should not be a serving member of the High Court." Mr Justice Moriarty said the tribunal had been temporarily brought to a halt by a "fait accompli" when Mr O'Brien did not turn up at Dublin Castle yesterday.
Referring to the birth of Ms O'Brien's baby by Caesarean section on Saturday, which has kept the witness from the tribunal, Mr Justice Moriarty said he fully understood the distress and concern experienced by Ms O'Brien during her difficult pregnancy. "I'm very gratified and pleased that the birth went satisfactorily and that mother and child are well," he said. However, he would offer no apology following his request for a medical report from Ms O'Brien's consultant gynaecologist.
"I do not in the circumstances propose to make any apology for what has taken place in this tribunal," he said.
In exercising his public duties as chairman, he found it necessary to seek the medical report, he said, which was the practice in civil or criminal court cases. It was not an indication that the tribunal was unresponsive to "domestic emergencies".
"I believe it would have been wrong in principle if I had not sought the medical report."
The judge said the details of the document, which will remain confidential, did indicate that there were matters of immediate concern for Mr and Ms O'Brien surrounding the pregnancy.
"I accept from the medical report that there were matters that justified some immediate respite for Mr O'Brien from the demands of testimony," he said.
However, he was unhappy with Mr O'Brien's decision to take two weeks off.
"I do consider it could have been possible for evidence to have resumed at least at some later stage this week rather than being deferred to Monday next," he said. "I'm regarding it as incumbent upon him that he will attend . . . on Monday next at 11 o'clock."