The Taoiseach has told the Mahon tribunal that the claim he lodged $45,000 in an AIB branch in 1994 is an "explosive" suggestion leaked to the media on the eve of the election.
Under questioning by tribunal counsel Des O'Neill SC, Mr Ahern said the false allegations made about him had been calculated to do "maximum damage".
The tribunal is investigating four bank lodgements to AIB O'Connell Street, Dublin, totalling over £84,000 in 1994 and 1995. All of the lodgements were preceded by foreign exchange transactions.
It is focusing on one payment of approximately £30,000 by Manchester businessman Michael Wall to Mr Ahern in 1994 to fund work on a house Mr Ahern was to rent from Mr Wall.
Mr Ahern, who was minister for finance at the time, has already said a significant lodgement made in 1994 was sterling. However, tribunal lawyers used AIB bank records to claim the lodgement was in dollars.
Mr Ahern's former partner, Celia Larkin, who made the lodgement on Mr Ahern's behalf on Monday, December 5th, 1994, said yesterday the money handed to Mr Ahern in St Luke's constituency office by Mr Wall was sterling. She had brought the money to the bank in a briefcase but had not looked inside the briefcase.
Today Mr Ahern said the dollars allegation had not been notified to him by the tribunal before his private meeting with tribunal lawyers. The first time he heard it was at that private session. He said he "emphatically" rejected the suggestion that day and did so again today.
Mr Ahern named Paddy Strong, former chief operating officer of Bank of Ireland Corporate Banking, as the currency expert he had engaged to examine the issue. He said Mr Strong's investigation did not substantiate the tribunal's theory that the lodgement was dollars.
It was a "matter of moral certainty" that there were no dollars, Mr Ahern said.
Commenting on the allegation made by developer Tom Gilmartin that he took money from Cork-based developer Owen O'Callaghan, Mr Ahern said: "I never got a glass of water from Mr O'Callaghan, not to mind money."
He said Mr Gilmartin had made "reckless and scurrilous" allegations against him, some that had not come into the public domain.
"You would appreciate . . . that I still feel sore about a lot of the other things he said about me."
He said it seemed to him unfair that if somebody makes 20 allegations and "19 of them are nonsense" that when it comes to investigating the last one, he should spend "the last three years of my life" dealing with them. But he told counsel for the tribunal: "Listen, I make the laws too, so I'm not arguing about that."
Mr O'Neill pointed out that Mr O'Callaghan had denied to the tribunal that he ever made remarks to Mr Gilmartin that he had paid money to Mr Ahern, and also denied that he had paid any money to Mr Ahern.
Mr O'Neill then took Mr Ahern through a series of documents and letters exchanged between the tribunal and Mr Ahern's solicitors, at a point when the tribunal was seeking information from him in 2005.
Mr Ahern said the information took "months and considerable hardship and knee-bending" on his part to put together. "I would have got it in a week if possible, but let's be fair," he said.
Mr Ahern said he didn't want it to be seen that "I was taking my time to do it."
He had to go into a "huge level of detail," and it took "all my personal time" for weeks, he said. It required compiling documents and bank statements and information from a period when he was also leader of the Opposition.
Going through the information was a "painstaking process", he said.
Mr Ahern said at the point when his solicitors and the tribunal were exchanging documentation, it wasn't the allegations about the "fifty thousand or the thirty thousand or the sterling" or any of those matters that worried him - "because I didn't get any of it".
"If I was losing sleep it was not about any of those issues - it was about the fact that this man [Tom Gilmartin] was saying all sorts of mad things - crazy things," Mr Ahern said. This included an allegation that Mr Ahern had "set up" two colleagues to blackmail someone, he said.
If that allegation had come into the public domain he "would've been finished", Mr Ahern added. He said that "if that had been leaked, I would have been in serious trouble".
Mr Gilmartin had been "down my neck" for the last seven-and-a-half years and he was making very serious allegations, the Taoiseach said. "Our issue was not a row with the tribunal," he added.
What he was worried about was the fact that, at that time, he was getting a "redacted" version of "what this man was saying" via correspondence from the tribunal. "And that's why you got the long-winded letters from my legal team," he added.
Mr Ahern told the tribunal later he did not accept that the lodgements he was asked about by the tribunal were not fully accounted for in a report provided to the tribunal by his accountant Des Peelo in 2006.
He said he and Mr Peelo believed the report furnished to the tribunal in April 2006 was a "comprehensive response" to the tribunal's inquiries.
Mr O'Neill SC for the tribunal said the fact was, up to that point, Mr Ahern had not provided an account of where the five large lodgements it was asking about had come from. He had provided bank documentation.
But Mr O'Neill said it was not "comprehensive information" in that the detail of it did not include all the questions that had been asked of Mr Ahern.
"I accept that," Mr Ahern said.
Mr O'Neill said it was not until later correspondence with the tribunal that Mr Ahern provided details of the amounts concerned, how they were received and how they came to be lodged in bank accounts.
Mr O'Neill put it to Mr Ahern that he had approached the matter of reconciling his accounts for the period 1993 to 1995 on the basis of trying to reconcile lodgements to his accounts with his salary cheques, ie, the Paymaster General cheques he received as a public representative.
But the lodgements in question "could not be related to any earnings of yours, isn't that correct?"
Mr Ahern replied that this was correct.