The Taoiseach is to give any money he receives from his defamation award to charity, saying his sole reason for taking the case was to clear his name.
Mr Ahern, who was awarded £30,000 in damages, plus costs, in Dublin's Circuit Civil Court, told reporters that he had not taken the case for money. Had he been seeking money, he would have gone to a higher court rather than to the Circuit Court, where the maximum damages award is £30,000, the amount he won.
He said he would give any money he received to charity. A spokesman said that the money would be divided equally between Focus Ireland, an organisation helping the homeless, and Temple Street Children's Hospital, which is in Mr Ahern's constituency.
However, sources close to Mr Ahern doubt whether any money will be paid over. Mr Denis O'Brien, the Cork businessman he sued, has maintained consistently that he has no money.
Mr Ahern won the damages after Mr O'Brien withdrew his defence in the case. Mr O'Brien claimed last year that he had handed over £50,000 in a Dublin hotel car-park in 1989. His allegations were published in the Sunday Business Post. He declined to comment after the case yesterday.
Awarding damages, Judge John O'Hagan described the allegations as "utterly, completely and absolutely false and untrue".
Mr Ahern said he did not believe in suing, but he had no alternative in this case. "A politician has to accept the fact that people will often say things about him which are unfair or distort his record. This is a normal part of the life of a democratic society.
"But no one has the right to spread malicious rumours and direct lies about a politician or any other person. Therefore, I had no alternative to taking this case in order to clear my name."
He said he hoped the verdict clearing his name would receive due prominence in the media in view of the "enormous publicity which his [Mr O'Brien's] false allegation received in the print and broadcasting media".
Mr Ahern said that while he had denied the allegation the day after it was made, some in the media had questioned whether his denial was accurate.
"I particularly want to thank the media who believed me at the time, because these things were fairly devastating. It said I was a fraud, a gangster. It said I was corrupt. It said I took white envelopes instead of brown. It said I used my position. A large part of the Irish media believed me, and I want to thank them for that."
Mr Ahern said that during his years as a public representative his only motivation had been public service.