As part of its inquiry into the allegation that Ahern received money from Cork businessman Owen O'Callaghan, the tribunal sought details of all his property transactions, whether beneficial to him or not, between 1 January, 1989, and 31 December, 2002. His lawyers replied to the tribunal in June 2006 that his sole property dealings had related to his former family home in Malahide and the controversial purchase of his current home in Beresford Avenue.

"We are instructed that, in the relevant period, there were no other property purchases or sales involving our client, " Ahern's legal team wrote.

But four months after that letter was written, the Taoiseach told the Dail that he had been party to another property transaction within the relevant time frame. The building was at 72 Amiens Street, the former Fianna Fail headquarters in Ahern's Dublin Central constituency.

While answering questions about his Beresford house sale in the Dail on 5 October, 2006, Ahern referred to a dormant bank account in his name at the Clonliffe Road branch of the Bank of Ireland and rejected a suggestion that it contained 30,000. He said he had opened the account in the 1970s in order to cash a cheque and never closed it.

"A journalist asked me whether I had the money from the sale of that house [72 Amiens Street] in my dormant account. The house was sold by the trustees and officers of the party and I probably was a trustee, " he said. "The money is in the accounts."

If Ahern's challenge to Mahon on the issue of parliamentary privilege is upheld by the High Court in April, the inquiry will be prevented from questioning him about the discrepancy between his reply to its correspondence and what he said in the Dail.

The leasehold on 72 Amiens Street was transferred into the trusteeship of Fianna Fail's three sitting TDs in the constituency . . . Ahern, John Stafford and Dermot Fitzpatrick . . . in June 1989, three weeks before it was sold to a company called Proximity Property Limited. Five months later, Proximity Property sold it on for about IR£130,000.

Ahern told the tribunal before Christmas that the purchase of his present constituency office, St Luke's in Drumcondra, was necessitated by the sale of 72 Amiens Street. However, documents in the Registry of Deeds show that St Luke's was acquired a year before the Amiens Street building was sold.

Asked by the Sunday Tribune to name the beneficiaries of the sale and to specify the "accounts"to which the proceeds were lodged, FF replied:

"The beneficiaries were three of the local constituency comhairles in Dublin. The proceeds of the sale were divided as agreed. The proceeds that accrued to Dublin Central are held in a constituency account."

The disclosure that Fianna Fail in Dublin Central only received one-third of the price fetched by the Amiens Street property raises new questions about the source of the money used to buy St Luke's.