A newspaper article published in 1983 claimed that Mr Haughey had owed around £1 million to Allied Irish Banks the previous year.
However, AIB said in a press statement the claim was "so outlandishly inaccurate" that it felt compelled to say so publicly.
Counsel for the tribunal, Mr John Coughlan SC, said the story was written by a "special correspondent" and published on page 7 of the Evening Press on January 28th, 1983.
It stated that Mr Haughey's financial affairs had been a matter of "intense public speculation since the first day he came into politics".
The article continued: "The suggestion that the bugged conversation between Mr Ray MacSharry and Mr Martin O'Donoghue referred to possible financial problems for Mr Haughey should he lose the leadership comes as no surprise." It had been rumoured in financial circles for years that Mr Haughey owed £1 million to a major bank and that the bank had held its hand because of his political position, according to the article.
Sources close to AIB were quoted as insisting that Mr Haughey had owed this sum in the previous year, 1982.
In response, the AIB issued a press statement on the matter and this was published in the Evening Press on February 1st, 1983, said Mr Coughlan.
The statement said AIB had a strict policy and a duty to maintain confidentiality regarding customers' dealing with the group and each member of staff completed a formal declaration in this regard.
Occasionally, statements were made by third parties which "appeared to be authoritative but are not". It could also be the case that a denial by the bank might itself be a breach of its duty of confidentiality and generally the bank felt it was best not to comment.
"Allied Irish Banks has found itself in this position on a few occasions recently. However, in the Evening Press on January 28th, in an article by a special correspondent dealing with financial affairs of a well-known figure, it was stated that sources close to Allied Irish Banks insist that he owed them around £1 million last year," said the statement.
"This statement is so outlandishly inaccurate that Allied Irish Banks feel bound, as a special matter, to say so positively and authoritatively.
"For the future, Allied Irish Banks would hope its commitment to the rule of confidentiality would be understood when it declines to respond to statements or suppositions put to it in the quest for information which it may not divulge."