The opposition has agreed that the allegations that the Taoiseach delayed the Flood tribunal for five years were "transparently nonsense".
But they accused the Taoiseach of "selling out the country" by accepting the Mayo TD, Ms Beverley Cooper Flynn, back into the party fold.
Mr Ahern accused the opposition of contriving "spurious political smoke" and insisted that he had never betrayed the trust or confidence of the electorate.
In a statement Mr Ahern dismissed as "absolute nonsense" a Sunday newspaper report that he had delayed the tribunal.
The Labour leader, Mr Pat Rabbitte, agreed that it was "transparently nonsense" but said the big issue was whether Beverley Cooper Flynn would be sacked.
"Are you going to sack her and when she gets her day in court and we hear due process, can you admit her? Isn't that what you do anyway with the ones who go voluntarily? Will you sack her or do you fear that when Mr Flynn goes into the witness box he may have some things to say that are not in accord with the historical record of the House?"
The Fine Gael leader, Mr Enda Kenny, accused the Government of sacrificing two of the fundamentals of democracy, public trust and citizen participation, "to advance its own political agenda and achieve its own political ambition".
He claimed that Mr Ahern "sold this country out when you took Deputy Cooper Flynn back into the Fianna Fáil fold, with allegations outstanding against her, to shore up his own political ambitions".
And Mr Kenny accused him of seeming "not just privately to have tolerated law-breaking, aberrant and gross misbehaviour in your party, you have actively and publicly rewarded it in some cases".
The Socialist Party TD, Mr Joe Higgins, said the Taoiseach "must now reach for the tribunals as he usually does, as a handy prophylactic to protect himself from legitimate questions which should be put in the House".
He said that the developer Mr Tom Gilmartin must have felt in 1989 that he was dealing with the "more dysfunctional wing of the Corleone clan", in reference to the Mafia.
He said Mr Ahern was a "treasurer, chief whip and senior Minister of Fianna Fáil and became the party leader. He found his way around the Fianna Fáil party as easily as a worn wheel around a greasy axle. It beggars believe that the Taoiseach did not know about the blatant greed that his senior Cabinet colleagues and county council colleagues were guilty of."
The Fine Gael leader said that governments "are elected to govern, not just to appease. They are elected to do what is right, not just what is popular.."
He said that elderly people and the homeless "listen to what happens in this House and they hear words, noise, jabbering and meaningless nit-picking over technicalities".
Mr Rabbitte said that, while for many years "our citizens believed that the purpose of government was to make them equal before the tax law, they find now that instead of making them equal before the tax law, government was indulging in the inequities of the tax law."
Now "we find that transgressions were occurring at the highest level of Government. A Cabinet Minister sent his wife into their local bank to lodge £50,000 in a bogus non-resident account, saying that their address was in Chiswick in London and giving a big wink. A Revenue form was then signed. This is almost unbelieveable, but it is the reality of which we speak."
He said that Mr Gilmartin, who had made the allegations about Mr Flynn, said that "every time he looked around somebody had his hand out, and he paid them".
But, the Labour leader said, "despite paying them, Mr Gilmartin was shafted and sent back to London with his tail between his legs while benefits were conferred on a rival developer. That is bad value for money on any basis, yet that is what happened."
