The AIB team appearing before the Dail Committee of Public Accounts yesterday strongly criticised the approach taken by the bank's former group internal auditor, Mr Anthony Spollen, to the issue of bogus non-resident accounts.

The chief executive of AIB, Mr Tom Mulcahy, disputed the suggestion by Mr Spollen that AIB had a DIRT liability of £100 million in 1991.

He said figures quoted by Mr Spollen "are over-estimations and seriously unreliable". He added that the assumptions on which Mr Spollen's figures were calculated "had no basis in fact and were selective".

"The figures were not Mr Spollen's own and were never intended as a precise measurement of the situation," he stated. He said Mr Spollen's figures were based on ones produced by Mr Jimmy O'Mahony, AIB's group taxation manager.

"Mr O'Mahony has described them as an off-the-cuff estimate to get people's attention," he said. He added that Mr O'Mahony had arrived at the £100 million to "fire up the organisation about the issue".

Mr Mulcahy said that Mr Spollen "simply worked over Mr O'Mahony's figures and that was his contribution". Responding to a question from Mr Sean Doherty (Fianna Fail) on why Mr O'Mahony arrived at the figure of £100 million for DIRT liability, Mr Mulcahy said he "inflated the figures to get the attention of the organisation".

Mr O'Mahony is now retired from the bank, while Mr Spollen works as a consultant to National Irish Bank.

Mr Philip Brennan, current head of AIB group taxation, said that Mr Spollen's figures were inaccurate in a number of respects. "He plucked the 60 per cent figure (the number of non-resident accounts which were bogus) out of the air and did not make any allowance for changes in interest rates," said Mr Brennan.

He said figures published in Magill magazine from audit material compiled by Mr Spollen were "flawed".

"He included foreign currency accounts as non-resident accounts; he included accounts where DIRT was being applied; and he included accounts which had no money in them," he said.

"It was a top-of-the-head calculation and not very scientific," said Mr Brennan.

Another member of the AIB team before the committee, Mr Kevin Kelly, managing director of AIB Bank, said that Mr Spollen was not involved "in the main part of the process" designed to deal with the issue of non-resident accounts.

He said Mr Spollen was involved for a long time in discussions concerning moving from his job as internal auditor and only "formed views" about the issue of bogus non-resident accounts when the discussions about his position were nearing conclusion.

Mr Kelly said a committee of non-executive directors, chaired by Mr Jim Culliton, had a private meeting with Mr Spollen in December 1990 and Mr Spollen did not raise the issue.

Mr Mulcahy added that it was not until February 1991 that Mr Spollen raised the issue and said the difference in his approach between the two dates "is very important". "I am not drawing any conclusions about that, but simply presenting it as fact," he added.

When asked did he consider Mr Spollen a "maverick auditor", Mr Kelly replied he was not, "but just happened to have a difference of opinion with the bank on this issue".

Mr Brennan and Mr Mulcahy did not accept the allegation that 17,000 certificates for non-resident accounts were missing from the bank. The allegation was made in the audit material published in Magill magazine.

Mr Spollen when contacted last night by The Irish Times declined to comment on the points raised by the members of the AIB team.