The Taoiseach, Mr Ahern, is expected to recall the Dáil before the end of the week to discuss the crisis in Iraq.
As the Opposition renewed pressure on the Government to confirm whether it will allow the US military to use Irish airspace and Shannon airport when war begins, one Fianna Fáil backbencher said such facilities should be restricted to sanction the US for breaking with the UN Security Council.
The Dublin north-west TD, Mr Pat Carey, said he was "extremely uneasy" about suggestions that the US would continue to support the Northern Ireland peace process in return for the use of Shannon.
He said: "When push comes to shove within probably the next 24 hours, we'll have to make a judgment call on whether Ireland's interests will be served by some continued availability of Shannon or whether it should be restricted."
In addition, the Carlow-Kilkenny TD Mr John McGuinness said the provision of services to the US should be discussed in advance by the Fianna Fáil parliamentary party. Such remarks suggest that the Government would face some internal opposition if, as expected, the Cabinet allows the US to use Shannon.
There was no indication last night that Mr Ahern would recall the Dáil before hostilities began. But with war imminent there was an expectation in political circles that this would happen on Thursday or Friday.
Generally speaking, the Government would be expected to provide 48 hours notice in advance of such a recall.
A Government spokeswoman said Mr Ahern discussed the situation a half-hour meeting yesterday with the Minister for Foreign Affairs, Mr Cowen.
Fine Gael's foreign affairs spokesman, Mr Gay Mitchell, said the Government should publish legal advice from the Attorney General if it was going to provide facilities at Shannon.
Mr Mitchell said: "It's unthinkable that it is not in session now.
"There are two institutions which should be shown respect at this time. The first is the UN. The second is the Dáil." He said the Taosieach should call the Dáil back before a meeting of the European Council next Thursday. Fine Gael leader Mr Enda Kenny rang the Taoiseach requesting that the Dáil be recalled.
Labour's foreign affairs spokesman, Mr Michael D Higgins called for an open-ended debate. He said: "There isn't a shred of legal basis for an individual country or group of countries to act in the name of the Security Council."
He added: "Kofi Annan has explicitly stated that any pre-emption would be outside the charter of the UN so where does the Taoiseach stand now?"
The Green's foreign affairs spokesman, Mr John Gormley, said the Government would apply "huge pressure" on any backbench TD who opposed overflight and landing services to the US after an invasion.
"If they ignore the 100,000 people who marched against the war, they will have to face terrible political consequences.