The Fianna Fáil leader Micheál Martin has insisted he never undermined the integrity of the Mahon Tribunal.
The final report, released yesterday, said attempts were made by Fianna Fáil Ministers in the past "to collapse" the inquiry.
Mr Martin said his party is "acting swiftly and comprehensively in response to the Mahon findings" by tabling motions to expel Bertie Ahern, Padraig Flynn and three councillors from the party.
He said there are no circumstances to justify Mr Flynn accepting a IR£50,000 payment and the Fianna Fáil leader said the comments relating to Bertie Ahern are "extremely serious".
Mr Martin said: "They do not set out specifics - I can't act as judge and jury in this.
"What I can say - and I would challenge anybody to produce any quotation to that suggestion - it is wrong and it would be wrong to, in any shape or form, undermine the Tribunal.
"In particular to try and undermine the integrity of the Tribunal, I would not, in any shape or form, condone that - and I would condemn it."