The chairman of Revenue Commissioners, Mr Dermot Quigley, has played down suggestions that there could be hundreds of millions more in tax to be collected from bogus non-resident account holders. Mr Quigley said the figure of £700 million (€888 million) which had frequently been used for the total outstanding "was not an official figure".

But, Mr Jim Mitchell, who was chairman of the Public Accounts Committee when it investigated the issue, said yesterday that the £176 million collected under the Voluntary Disclosure Scheme "is only the tip of the iceberg". The Fine Gael deputy leader and finance spokesman did not suggest a figure on how much more tax he believes is outstanding.

It is impossible to work out how much could still be owed, according to Mr Quigley. The £700 million figure - which was quoted in internal Revenue Commissioners documentation - was reached by extrapolating the results of an investigation into one bank branch in Milltown Malbay, Co Clare. It took no account of the possibility that many of the bogus non-resident account holders may have already participated in the 1993 tax amnesty. Some 40,000 people took advantage of the amnesty to settle tax bills on more than £600 million of undeclared income, said Mr Quigley. Anyone who used the amnesty to sort out their non-resident account problems would no longer have a liability, he said.

A small number of people had already come forward under the voluntary scheme and disclosed that they held a bogus non-resident account, but had declared them under the 1993 tax amnesty. The Revenue Commissioners also believe that the majority of the people who did not avail of the Voluntary Disclosure Scheme - which closed last Thursday - would be small account holders.

"I suspect a lot of the bigger cases have settled," said Mr Quigley. Eleven people made payments in excess of £1 million while another 60 paid over £500,000, he said. Tax payers who took advantage of the voluntary scheme were allowed settle all their tax liabilities under the favourable terms of the scheme, not just the underlying tax owed on the money in the non-resident account. They were required to pay all the tax owed on the money in the account plus interest and penalties, but as an incentive the interest and penalties were capped at 100 per cent of the tax owed. Individuals with large liabilities would have been told by their banks that the Revenue Commissioners were looking at their affairs, said Mr Quigley. The look-back audit carried out by the Revenue Commissioners last year to assess the banks' liability for not collecting Deposit Interest Retention Tax on these accounts would have concentrated on the larger accounts, he said. The look-back audit collected £173 million from banks and building societies.

So far, £349 million has been collected, which, Mr Mitchell pointed out, was good value for the taxpayer. The PAC inquiry cost £1.8 million and the Revenue have spent £1.25 million publicising the current voluntary disclosure scheme.