An "overview team", made up of the most senior officers in the Revenue's investigation branch, is investigating the affairs of the 120 individuals linked to the Ansbacher deposits.
The team, which includes the head of the capital taxes branch, is also investigating others associated with the 120, as well as companies and discretionary trusts, professional advisers and financiers.
The 120 individuals are named in a confidential report into Ansbacher written by authorised officer Mr Gerry Ryan. Permission for 21 Revenue officers to have access to the report was granted by the Minister for Finance, Mr McCreevy, in October 1999.
The Revenue officers have also been allowed to view documents produced in other authorised officer inquiries into Guinness & Mahon bank, Irish Intercontinental Bank, Hamilton Ross, (of the Cayman Islands), Kentford Securities, Dunnes Stores Ireland, Dunnes Stores (ILAC Centre), Faxhill Homes, Celtic Helicopters and Garuda.
The 21, whose names are listed in documents released following a request under the Freedom of Information Act, include seven senior inspectors of taxes, 11 higher grade inspectors of taxes, and four inspectors of taxes.
Another seven officers have also been granted authority to view the same document. These are Mr Dermot Quigley, Revenue chairman, Mr Christopher Clayton, chief inspector of taxes, two assistant secretaries, two principal inspectors and a principal officer.
The inquiries into the two Dunnes Stores companies have been delayed more than two years because of legal challenges brought by the group. Faxhill Homes is a company which carried out work, paid for by Dunnes Stores, on the home of Mr Michael Lowry. Mr Lowry owns Garuda.
In October 1999, the Revenue sent inquiry letters to the persons identified in Mr Ryan's Ansbacher report. "It is clear that a very considerable amount of investigative work will be required by the Revenue," Mr Quigley said in a letter to the outgoing secretary general of the Department of Finance, Mr Paddy Mullarkey, in October 1999. He was seeking permission for the 21 officers to see the confidential documentation.
"In expanding the investigation we are anxious to take all reasonable precautions to ensure that only duly authorised officers gain access to material so that, for example, there will be no technical problems in the event of prosecutions."
Mr Quigley also said the officers should have access to documentation from all the inquiries mentioned above "because of the apparent linkages between the Ansbacher inquiries and other companies mentioned in the schedule".
Internal Revenue documentation states the investigating staff "will have appropriate back-up by way of research etc, for example discretionary trusts, by experienced special inquiry and other officers. Capital taxes branch and the anti-avoidance unit will also be involved".
The Ansbacher deposits operated as a secretive financial service from the early 1970s to 1997 which is believed to have facilitated large-scale tax evasion. The deposits, operated by the late Mr Des Traynor, were used by some of the State's wealthiest figures.