Fine Gael leader Enda Kenny challenged the Taoiseach's positive references to Charles Haughey's legacy.
Mr Kenny said that no mirror could reconcile the utterly contradictory views of Mr Haughey. Mr Justice Moriarty had said he considered Mr Haughey to have "devalued the quality of modern democracy".
Meanwhile, Mr Ahern had expressed the view that Mr Haughey had "a proud identity with Ireland" and was "a patriot to the core".
Mr Kenny accused the Taoiseach of reconciling patriotism with the abuse of power and of the institutions of the State, not to mention taking money from friends for private use in public life.
"I cannot. Because, for me, with power comes responsibility, the responsibility to apply the highest standards of probity. Power is always problematic. It is not always exercised benignly, justly or morally, as this report confirms.
"And because it does, it is a damning indictment of former taoiseach Haughey, far more damning that we might have expected." Mr Kenny said the report was a devastating critique of a powerful elite.
It had exposed a gross abuse of privilege, a rank abuse of public office, and, most importantly of all, a devastating abuse of public trust.
Mr Justice Moriarty, he said, had returned a devastating verdict on Mr Haughey.
"However, to see Mr Haughey's behaviour as an aberration within Fianna Fáil would be an affront to the tribunal, and, indeed, to every democrat in this country. Because far from being an aberration, Mr Haughey's behaviour and attitude typified the culture of Fianna Fáil at a significant period.
"Where Raphael P Burke accepted corrupt payments related to radio licences, where there was serious corruption of the planning process, and where funds, donated to Fianna Fáil for the practice of democratic politics, were misappropriated."
To Fianna Fáil, said Mr Kenny, it was all just business as usual, and there was the abiding sense, and the abiding evidence, that there were many in the inner circle who wanted, and felt, that they deserved a piece of the action.
"More disturbing still is the current Fianna Fáil leadership's refusal to condemn the actions of their former colleagues." Mr Kenny said that while some in public life equivocated about Mr Haughey, the report did not.
"At the core of this valuable work, there is an uncovered ruthlessness, an ambition, a sense of force and cunning, more in keeping with how a banana republic operates, than how one of the world's most modern and newest republics operated, for periods, up to a decade ago. Repressive, secretive, corrosive and, now with Moriarty, corrupt. In that context, the report is an eyewitness to misery.
"The everyday lives of the ordinary Irish people, who tightened their belts to the buckle, who paid mortgages at 16 per cent, tax at 58 per cent, collected dole at £42 a week, while the more docile, biddable cohort of 'loyalists' scuttled along their party and departmental corridors, signed blank cheques while Ireland was broke, who put up and shut up, watching their leader, immaculate in Charvet, 'smile and smile and be a villain'."
Mr Kenny said that until the men and women who filled the current Fianna Fáil benches were willing to declare publicly that what Mr Justice Moriarty had uncovered within the party was never right, always wrong, was never justifiable, always inexcusable, "they must be associated with the culture of corruption that characterised Fianna Fáil for such a long time, including in government".
