Mr Justice Moriarty yesterday complained of "strange and troubling" differences in testimony given by witnesses at the tribunal recently.
His comments followed the conclusion of the cross-examination of Mr Michael Tunney, a former executive with GE Capital Woodchester Bank.
Mr Tunney was further questioned about the £420,000 sterling loan granted in 1999 to a British-registered company, Catclause Ltd.
The judge said he did not understand the witness's assertion that Mr Denis O'Brien was "globally" behind Mr Aidan Phelan in Mr Phelan's dealing with the bank. "I freely admit it's not the easiest of concepts for me," Mr Justice Moriarty said.
Mr Tunney had earlier told the tribunal Mr O'Brien was "behind Aidan Phelan as a supporter" and in a "global sense".
"He was a big income-generator for him . . . He was not specifically involved in this transaction," he said.
Mr Tunney said he was shocked when Mr Michael Lowry, the former Fine Gael minister, turned out to be a director of the Catclause company. He learned of Mr Lowry's involvement from his former boss, Mr Michael Cullen.
One week later he went on a skiing holiday in the same town as Mr O'Brien. However, Mr Tunney did not discuss the matter with Mr O'Brien for a number of days.
Mr Jeremy Healy SC, for the tribunal, asked Mr Tunney why he did not mention it immediately.
Mr Tunney said he had to establish all the facts of the matter before saying anything. He then spoke to Mr O'Brien after a phone call with Mr Cullen.
What had Mr Cullen said that prompted him to speak? Mr Healy asked.
"We were talking about the big `M' . . . and that it was necessary to speak to him at this stage," Mr Tunney said.
Mr Tunney said he knew of no reason why Mr Phelan would not have told him the money was for Mr Lowry, "other than it would make it more difficult to get the loan".
Mr Healy said: "He was leaving you holding the baby with a very unsatisfactory borrower . . . Not just to tell you a lie, it was to pull a fast one on you, isn't that right?"
"Potentially," Mr Tunney answered.