Cash lodged with AIB on behalf of Bertie Ahern in December 1994 equates exactly to $45,000 when one of the dollar exchange rates used by the bank on the day is applied, the Mahon tribunal heard yesterday.
The Taoiseach has said several times that he was not involved in any dollar transactions.
The £28,772.90 was lodged by the Taoiseach's then partner, Celia Larkin, to an account she opened in her name and was preceded by a foreign exchange conversion.
While Mr Ahern and Ms Larkin have said the lodgment comprised a large amount of sterling cash, and no dollars, the records at AIB O'Connell Street, Dublin, show that the value in punts of all the sterling lodged there on the day in question was just £1,921.53.
Mr Ahern and Ms Larkin have said the lodgment took place after Manchester-based businessman Michael Wall gave Mr Ahern stg£30,000 in cash. The money was to be used on the renovation of a house Mr Ahern was to rent from Mr Wall.
The tribunal began hearing evidence yesterday in its public inquiry into transactions involving Mr Ahern in the early 1990s when he was minister for finance.
AIB foreign exchange expert John Garrett gave evidence and is to be cross-examined by counsel for Mr Ahern tomorrow. A number of bank witnesses are to be called this week and next week. Mr Wall, Ms Larkin and Mr Ahern are due to give evidence next week.
Bank documentation shown at the tribunal yesterday called into question three aspects of the account Mr Ahern has given concerning lodgments on his behalf to AIB O'Connell Street, Dublin, in 1994 and 1995.
Mr Ahern has said the December 1994 lodgment was sterling but the bank's records do not support that.
A lodgment in October 1994 which Mr Ahern has said was made up of stg£8,000 and £16,500 equates to stg£25,000 exactly when one of the sterling exchange rates in operation on the day is applied.
Bank records do not record a sale of stg£30,000 in the first six months of 1995.
Mr Ahern has said two sterling lodgments he made in 1995 were the re-lodgment of money he withdrew, converted into sterling, held for a period of time, and then re-lodged.
The tribunal is conducting what chairman Judge Alan Mahon has described as a "ring-fenced" inquiry into a number of large cash lodgments made by Mr Ahern, or on his behalf, in 1994 and 1995.
The inquiry is focused on a number of foreign exchange transactions which preceded these lodgments. AIB has not been able to locate any surviving records that document the actual foreign exchange transactions.
However, tribunal counsel Des O'Neill SC asked Mr Garrett questions based on other documents the bank has managed to source, including records of Mr Ahern's accounts, some internal documentation recording lodgments to those accounts, and records showing overall foreign exchange movements in AIB O'Connell Street on the dates in question.
The records show the bank conducted a very modest amount of foreign exchange business each day, though on the day in December 1994 that Ms Larkin made her lodgment, sufficient non-sterling currency was bought by the bank to accommodate a $45,000 lodgment. On most days the bank purchased sterling cash to a value of approximately £2,000, and non-sterling currency with a similar punt value, the tribunal heard.
Last week counsel for Mr Ahern argued that the tribunal hearings into his affairs should not go ahead. The chairman rejected the submission and Mr Ahern has not appealed that decision.