The Taoiseach has known for a month that Fianna Fail backbencher Mr Denis Foley was being questioned by the Moriarty tribunal, a Government spokesman said last night.
Mr Ahern was formally told of this "at Christmas", the spokesman said, but it could not be ascertained last night what action, if any, he took upon receiving this information.
The spokesman said that while the Taoiseach knew Mr Foley was being questioned, he did not know until yesterday that Mr Foley had held an Ansbacher account.
Mr Foley may be questioned at the Moriarty tribunal today following his dramatic resignation last night as vice-chairman and member of the Public Accounts Committee (PAC). His resignation followed the revelation at the Moriarty tribunal that he had held one of the controversial Ansbacher accounts.
The tribunal heard yesterday that Mr Foley invested £50,000 in the offshore Ansbacher deposits in 1979 and a further £24,000 in December 1990. Documents displayed at the tribunal showed that until recently the balance on his account was £135,000 sterling.
Mr Foley, who sat on the six-member PAC sub-committee which conducted the DIRT inquiry, is currently in discussion with the Revenue in relation to this account and recently handed over £50,000.
Mr Foley last night said he was resigning from the PAC because he did not wish to distract in any way from the good work of the committee.
A Government spokesman said the Taoiseach had instructed a party official to ring Mr Foley yesterday morning to ask him about the revelation, and that upon receipt of the call, without being put under any pressure, Mr Foley had said he intended to resign.
The revelation concerning Mr Foley led to deep Government annoyance on the day the Mr Ahern was announcing a Cabinet reshuffle.
The members of the PAC subcommittee were interviewed by its legal team before taking up their positions, but Mr Foley did not declare his potential conflict of interest.
Asked by The Irish Times on a number of occasions recently, Mr Foley denied any connection with the offshore accounts run by the late Mr Des Traynor. Calls to his office at Leinster House yesterday were not returned.
The revelations about Mr Foley came during an opening statement yesterday from counsel for the Moriarty tribunal, Mr John Coughlan SC. Mr Foley's involvement with the deposits was not discovered by the authorised officer, Mr Gerard Ryan, whose report was given to the tribunal. It only learned of his involvement late last year, when documents which had not been previously disclosed came to its attention.
The tribunal also heard that a convicted Cuban drug-smuggler received a $1 million loan from Guinness & Mahon bank in the 1980s, following his being introduced to the bank by its Cayman Islands subsidiary. The loan to Fernando Pruna was backed by funds lodged in Dublin by Guinness Mahon Cayman Trust.