The property developer Mr John Byrne said he never authorised his financial adviser, Mr Des Traynor, to back a loan to a company he directed with offshore funds.
Mr Byrne said the circumstances in which the Guinness & Mahon loan was repaid from offshore funds in 1985 were "all most mysterious" to him.
The tribunal also heard that Mr Byrne had not succeeded in getting any documentation about his offshore financial transactions from the trustees of his Cayman Islands trust.
Mr Byrne recalled the circumstances in which he became involved in the purchase of the Central Hotel and ballroom in Ballybunion, Co Kerry. The property developer said he became aware around 1972 that the hotel "had run into difficulties".
Mr Byrne, Mr Denis Foley and Mr William and Mr Thomas Clifford agreed to become directors of Central Tourist Holdings, which was formed for the purpose of purchasing and developing the Central Hotel. Each of the directors put up £5,000 each, and a £70,000 loan was raised from Guinness & Mahon.
The only securities Mr Byrne remembers being requested by the bank were "joint and several guarantees" from the four directors.
He said the loan was only supposed to be short-term. "Ballybunion at the time was very prosperous, and I think the directors thought they would be in and out of their borrowings very quickly."
He told the tribunal: "I do not recall any arrangement being put in place for a back-to-back deposit with Guinness Mahon Cayman Trust Limited."
In Guinness & Mahon documentation the loan was described as "suitably secured". Mr Byrne accepted that this expression "was used as shorthand by Guinness & Mahon to indicate the presence of a back-to-back arrangement", but said he would have expected Guinness & Mahon to be able to furnish some documentation proving such an arrangement existed.
"I am quite happy to accept the fact that Mr Traynor may have put in place some arrangement of a back-to-back nature, but I do not recollect this happening, though I accept it could well have happened", Mr Byrne told the tribunal in a statement.
He said he had only become aware when the tribunal wrote to him that Central Tourist Holdings debt which had by then grown to £135,000 had been discharged by Guinness & Mahon Trust Limited.