If parliamentary inquiries were to be successful there would have to be less political point-scoring, which undermined natural justice, according to the outgoing chairman of the Public Accounts Committee, Mr Jim Mitchell.
Citing the case of the Mayo TD, Ms Beverley Cooper Flynn, Mr Mitchell said yesterday there had been some examples in recent weeks which had been gleefully taken up by the media but which would not "pass muster in a court of law".
"If parliamentary inquiries, or other parliamentary for a are to be successful and credible adjudicators, there will have to be less political commentary and political charges being made publicly.
"Scoring political points can pre-empt natural justice and undermine the credibility of the adjudicating process," he said.
Mr Mitchell was presenting the third and final report of the DIRT inquiry which recommends that a commission be established to examine all aspects of parliamentary inquiries and tribunals of inquiry.
"I believe that this is an important and urgent necessity if we are to refine and define both forms of inquiry with a view to improving their context, their effectiveness, including cost-effectiveness, and their credibility," Mr Mitchell said in his resignation speech.
Some parliamentary colleagues had called on the Taoiseach, Mr Ahern, to take action against Ms Cooper Flynn.
"Whatever the ultimate findings in this case the rules of fairness and natural justice should be allowed due process, and any parliamentary findings in relation to her should be based on fact and not political charge or pressure," he said.
Political debate in relation to evidence at the tribunals was carried out "as if the untested evidence was an established fact, or was the complete story".
He said the PAC was concerned about the cost of the tribunals and their effectiveness. "The tribunals are going on for too long, and their sitting hours are too short. I have forgotten some of the evidence we heard at the beginning. I get the tribunals mixed up."
The publication of the final report, Mr Mitchell said, marked the last act of the first parliamentary inquiry in the Republic's history. The DIRT inquiry, he said, had cost around £2 million, with just £800,000 of that spent by the committee and around £1 million by the Comptroller and Auditor General.
The Minister for Finance, Mr McCreevy, said his Department had received a copy of the report. Once it had been studied proposals would be made to the Government.