The Taoiseach has described the leak of information on his financial affairs to The Irish Timesas "sinister" and "calculated".
Commenting at the presentation of the latest NESC report on Migration policy, Mr Ahern said that he had co-operated with all requests from the Mahon tribunal.
He said he had "supplied extensive material, fully and freely, to assist them in fulfilling the terms of reference which my Government put forward and which we fully support".
But he added that to carry out its work, a tribunal "in the interest of fairness to respect of all citizens" should be allowed to conduct their investigation properly in confidentiality.
He went on to say that a "calculated leak, from whatever source, can distort the procedures, [and] are in my view sinister and constitute a threat to the rights of the citizen and a threat to the integrity of the tribunal".
Mr Ahern made it clear that he continued to fully co-operate with the Mahon tribunal whenever necessary and that he had "given full and comprehensive information about all my financial and personal affairs over many years which they have required or which might be of interest to them".
He said all of that material is "available to the tribunal and it is for them to assess the significance or relevance." If the tribunal required any more information, "all they have to do is ask or write to me," he said.
Labour Party spokesman on the environment Eamon Gilmore called Mr Ahern's comments "outlandish claims". He said that the leaking of tribunal material was wrong but it was "not the first such leak, nor indeed was Mr Ahern the first victim of such a leak".
Mr Gilmore went on to point out that Mr Ahern - apart from his "vigorous endorsement of the finding of the McCracken tribunal that public representatives should not be under a personal obligation to anyone" - had gone further and quoted Mr Ahern speaking in the Dáil on December 3rd, 1996.
Mr Ahern was quoted as saying: "In principle, apart from token presentations in respect of functions performed at home or abroad, neither politicians nor officials should accept personal gifts of value from outside their family."
"Why cannot the Taoiseach say simply, who gave him the money, for what purpose was the payment made and how much was involved?" he said.