THE judge who was appointed as High Court inspector into the Ansbacher affair held an account at the bank at the centre of the offshore tax evasion scandal, a whistleblower claims.
The civil servant, who was heavily involved in the probe into the Ansbacher accounts, alleges a cover-up in relation to his claims.
The whistleblower's key allegations are:
• Declan Costello, a former Fine Gael TD, Attorney General and High Court judge and son of former Taoiseach John A Costello, who was appointed as a High Court inspector into Ansbacher, held an account with Guinness & Mahon bank, which was at the centre of the offshore tax evasion scandal.
• Former Fianna Fail and Fine Gael ministers held Ansbacher accounts, which were not revealed by an investigation into the offshore tax evasion scheme.
• The Moriarty Tribunal did not properly investigate Ansbacher - a state of affairs that undermines the integrity of the tribunal and the reliability of its findings.
The startling claims about a series of living and dead political figures are contained in a dossier sent to the Dail Public Accounts Committee (PAC).
He says he forwarded the allegations to ministers in three successive governments, including a serving Cabinet minister, but action was not taken.
However, eight years ago the claims were passed to the Revenue Commissioners, Garda Siochana, the Office of the Director of Corporate Enforcement, the Moriarty Tribunal and the Mahon Tribunal.
A file was sent to the DPP at the time.
The new dossier outlining the allegations has been sent by registered mail to each member of the PAC.
The Taoiseach last night said claims about tax evasion would be fully examined.
In the dossier, the whistleblower provides copies of bank account details of Mr Costello, which he claims, show transactions and interactions with Des Traynor.
Mr Traynor was the accountant who set up offshore Ansbacher accounts, allowing hundreds of well-heeled individuals to evade tax.
"Mr Declan Costello had a major conflict of interest as described above when he accepted the nomination and acted as a High Court inspector," he says in the dossier.
But Mr Costello was contacted by the whistleblower and denied carrying out any banking business with Mr Traynor.
The long-serving civil servant also alleges the Fianna Fail and Fine Gael figures named held Ansbacher accounts in the Cayman Islands - but were never properly investigated by State agencies.
The dossier gave details of the alleged existence of a ledger held by Mr Traynor, allegedly used to record details of these senior politicians.
The names of the politicians listed in the dossier, living and dead, are known to the Irish Independent.
Last night one of them denied he had engaged in tax evasion using offshore accounts. A close relative of one of the deceased politicians said she "very much doubted" the allegations.
The whistleblower also says the allegations in his 30-page briefing document may be relevant to the defence of the State and Michael Lowry and Denis O'Brien in the case being taken by the failed bidders in the 1995 mobile phone licence competition.
He alleges the ledger was not properly investigated by authorities, including the Moriarty Tribunal.
"The information contained in the briefing note shows that the Moriarty Tribunal failed properly to investigate significant evidence brought to its attention ...
"This failure has the potential to be seen as seriously undermining the integrity of the tribunal and the comprehensiveness and reliability of its findings."
He made the allegations under the new protected disclosure legislation, which allows whistleblowers to come forward without fear of reprisal.
He says he came across the information in the course of his official duties, but was instructed to terminate his inquiries before completing his work.
The information was first raised with a government minister several years ago, the whistleblower claims.
"I am of a view that this department has a duty to inform the High Court that the Ansbacher High Court investigation, led by Mr Declan Costello, did not uncover any evidence of the existence of the most important Ansbacher ledger maintained by Des Traynor in Guinness & Mahon."
The Taoiseach said he had not seen the dossier but he said that PAC has now asked for legal advice. He noted a garda statement that the matters had been investigated in the past.
PAC is likely to decide on a course of action when it meets again next Wednesday.
The chairman of the committee, John McGuinness, indicated it would be taking a cautious approach.
Sources said the most likely course of action would be for the dossier to be passed to the gardai.
Gardai last night confirmed that the allegations had already been investigated by the Garda Bureau of Fraud Investigations. A file was passed to the DPP.