The Government will need only an Oireachtas resolution to move parts of the Flood planning corruption inquiry into new commissions of investigation, it has emerged.
Legislation to set up the commissions, which will carry out their work in private, will be brought to the Government on Tuesday.
The legislation does not embrace any proposal to restrict the Flood tribunal.
Government sources said an Oireachtas resolution would be enough to remove certain modules from the tribunal. Such a manoeuvre would be relatively simple given the Government's majority in the Dáil.
But with some of the most politically-sensitive allegations yet to be aired in public by the tribunal, Fine Gael has warned that "the concern of many will be that potentially embarrassing modules of the planning inquiry will be transferred to private hearings".
These include allegations by British-based builder Mr Tom Gilmartin about his dealings with Mr Ahern and former EU commissioner Mr Padraig Flynn.
Mr Gilmartin has alleged that he gave £50,000 (€63,500) to Mr Flynn, an allegation he denies. He also alleges being asked after meeting with most of the Cabinet in 1989 to lodge money in an Isle of Man bank account.
The Fine Gael leader, Mr Enda Kenny, said that any move to transfer "embarrassing modules" would "seriously undermine public confidence in the inquiry".
He said in the Dáil: "It would be regrettable if the Government were to use its majority in this House to seek to hide from public view matters that are potentially damaging to particular political parties."
Responding, Mr Ahern said that he had assured the Oireachtas that he would "consult fully" on this matter.
The chairman of the tribunal, Mr Justice Flood, is considering a request from the Government for him to determine costs arising from the hearings to date. His response is expected soon.
Despite reports that he had said he would stay an additional two years, the Government indicated late last night it had not yet heard from him in relation to this.
The tribunal has sent a response, however, to a request from the Government to estimate the amount of time now required to complete its work, and to project the likely cost of such hearings.
A Government spokeswoman would say only that it was being considered.
It had sought information on the likely duration of the modules not yet heard amid concern that the overall inquiry could continue for another 15 years.
While Mr Justice Flood had stated that he wished to avoid the strain of determining costs, Mr Ahern said in the Dáil yesterday that the Government wanted him to rule on costs to minimise the risk of legal challenge. He said such challenges were inevitable if Mr Justice Flood did not make a ruling on costs.
The Taoiseach's remarks followed the confirmation from the Minister for Justice, Mr McDowell, that he was preparing to publish legislation to enable the establishment of commissions of investigation.
Such commissions would hear evidence in private, although their reports would be public. While the Government intends to facilitate a non-adversarial approach, informed sources said the commissions will have power to compel witnesses to give evidence and produce records.
Mr Ahern said that the allegations made by former lobbyist and government press secretary Mr Frank Dunlop should be heard by tribunal. "If we talk of any modules moving over, they will be later modules, and we must discuss whether this is possible."