The Taoiseach has denied being aware anybody from his office had contacted Fianna Fáil councillors over a North Dublin rezoning plan.
On what should have been an ordinary Monday of public events, Mr Ahern was questioned over the alleged role his former special advisor played in securing approval for the rezoning of Santry Demesne.
Speaking at the opening of a housing development project in Dublin, Mr Ahern said he did not see anything controversial in the matter because Fianna Fáil councillors voted in the same way as they would have done all along.
The Irish Independenttoday reported that in 1998, Mr Paddy Duffy, then special advisor to Mr Ahern, made phones calls from the Taoiseach's office lobbying Fianna Fáil councillors to vote in favour of the rezoning plan.
Mr Duffy has denied the allegations, according to the report. Mr Bill Kilmurray of Woodford Developments, who bought the land for development, was also reported to have denied having any contact with Mr Duffy on the issue.
Opposition parties have called on the Taoiseach to respond to the allegation with a full account of all parties involvement in the rezoning plan.
Fine Gael’s Mr Brian Hayes called on Mr Ahern to make an "urgent statement" on the "worrying revelations".
Mr Hayes said the Taoiseach must clarify if Mr Duffy had contacted councillors and, if so, whether he aware of his advisor’s actions. Mr Hayes also asked if Mr Ahern, or anybody on his behalf, had discussions at nay time with the beneficiary of the rezoning plan.
Labour spokesman on the environment Mr Eamon Gilmore said the allegation was "a matter of utmost seriousness that requires an immediate response from Mr Ahern".
He said: "If this was done with Mr Ahern’s knowledge then a clear explanation is required from him as to why he was involved himself in such a matter. If it was done without Mr Ahern’s knowledge then it clearly raises questions aobut what supervision or control was exercised over staff in his office".
In June 1999, Mr Duffy resigned as the Taoiseach’s special advisor it emerged he was a director of a public affairs company, Dillon Consultants, which advised NTL on its purchase of Cablelink from RTÉ and Telecom Éireann.