The Taoiseach, Mr Ahern, has said he found it hard to believe that senior figures at Ireland's biggest bank, AIB had not known the whereabouts of their foreign investments.
In a Dáil comment on the bank - where a number of past and present executives have admitted "tax issues" over the investments and some customers have been overcharged - the Taoiseach said: "I do not understand how people at the very top of these institutions could be involved without knowing anything about it".
Meanwhile ,the Central Bank Governor Mr John Hurley said events at AIB "very serious and deeply disappointing".
But Mr Hurley told an Oireachtas Finance committee that new control systems meant that similar incidents were less likely in the future and they would more quickly detected if they did occur.
Mr Hurley warned about "the danger of missing the improvements that have taken place".
Members of the committee strongly attacked a decision by the AIB not to appear before them ahead of an investigation into the latest allegations about the company.
The bank's decision not to attend the committee to discuss the scandals has been severely criticised by a number of members of the committee.
The Revenue Commissioners and the Irish Financial Services Regulatory Authority (IFSRA) established inquiries into AIB activities last week.
IFSRA, which has indicated that its investigations are nearly complete, said it would be examining all issues that have now been raised. The Revenue Commissioners said its investigation will be led by its investigations and prosecutions division and will include officers from the large-cases division.
Speaking on RTÉ News today, the Director of Corporate Enforcement, Mr Paul Appleby, said his office was informed of the revelations at AIB last Thursday shortly before a public statement from AIB.
"There are a couple of issues with respect to the events in question which we are anxious to examine," he said. He confirmed his office had asked for certain information from AIB, adding he was "expecting to obtain full co-operation from AIB".
He said that his office was concerned primarily with issues related to Irish investment managers, rather than the AIB group as a whole but declined to be specific about the details of the inquiry.