The contents of documents from the files of his family's solicitors William Fry were "mumbo jumbo" to him, businessman Denis O'Brien snr told the tribunal.
Mr O'Brien was unable to explain references to Michael Lowry and Denis O'Connor in file notes in the firm, including in a note that stated it was to be sent to Mr O'Brien snr.
The tribunal is inquiring into the purchase of Doncaster Rovers Football Club Ltd in 1998 for stg £4.3 million (€6.3 million) as part of a project aimed at moving the team to a new stadium and redeveloping the site of the old stadium. Denis O'Brien jnr has said it was his deal exclusively.
The tribunal is inquiring into whether former government minister Mr Lowry might have had a connection with the transaction. Both Mr O'Brien jnr and Mr Lowry have informed the tribunal that he had no connection.
John Coughlan SC, for the tribunal, showed Mr O'Brien snr a file note dated June 2002, written by Owen O'Connell, a senior partner in William Fry.
The note read: "Concern about DOB making payment to KP in circumstances of current tribunal where KP a potential witness [ hostile to DOB]."
KP is a reference to Kevin Phelan, a Northern Ireland businessman who spotted the commercial potential of the Doncaster deal, and who was later in dispute with the O'Brien family over fees he was claiming from Westferry, the O'Brien company that owned Doncaster Rovers.
The note continued: "Concern heightened by apparent collaboration with ML/ML adviser in making larger payment.
"Recommendation is to ask ML not to make any payment in anticipation of DOB contribution and to exclude DOB/Westferry from any deal/settlement he may reach, telling KP to make a written claim against Westferry.
"If this is rejected, before any payment is made, follow steps in previous note, of which key ones are to establish DOB ownership (ie beneficial) of Westferry and get written evidence of Westferry indebtedness to KP in excess of proposed payment."
Mr Coughlan said it was presumed the adviser referred to in the note was Mr Lowry's accountant, Denis O'Connor.
Mr O'Brien snr, responding to the note, said: "What the hell is that about? I haven't a clue . . . If he's writing to me, surely I would have been aware of something going on regarding payments. I've never seen it." .
"When I was dealing with Doncaster, nothing like that every took place . . . Honestly, this is complete mumbo jumbo to me."
Mr O'Brien snr noted that he was on oath and said that during his efforts to sort out the Doncaster dispute, he never spoke to Mr Lowry. "He never entered it."
Mr Coughlan showed Mr O'Brien snr a letter he had sent to Owen O'Sullivan of William Fry's, in June 2002.
The letter in part reads: "I have again spoken with Denis O'Connor and asked him, for his part, to have prepared a legal comprehensive letter in draft form, covering all aspects of the matter in which he has been involved (with the exception of Westferry), and he has promised to give this his immediate attention".
He said he had no recall of the letter but it was his letter. "I'm at a total loss as to what this is all about," he said.
The tribunal was shown a June 2001 letter from Mr O'Connor to Aidan Phelan, an accountant who acted as an agent in the Doncaster Rovers Football Club project. In the letter, Mr O'Connor said he had met Kevin Phelan. The letter stated that Mr O'Connor told Kevin Phelan that he, Mr O'Connor, knew nothing about the Doncaster project.
The letter covered discussions between Mr O'Connor and Kevin Phelan concerning other sites Mr Lowry and Aidan Phelan had dealings with.
The letter said Mr O'Connor was told by Kevin Phelan that he was claiming £156,200 in relation to Doncaster.
"Again, and he accepts this, it is nothing to do with me," the letter stated. Mr O'Connor stated in the letter that he was anxious, at Mr Lowry's request, to settle the deals Mr Lowry was involved in.
