Taoiseach Leo Varadkar has been warned a second "emergency budget" will be needed next year if a Brexit breakthrough fails to materialise amid growing fears a no deal crisis could cost the State €3.6bn.
Fianna Fáil leader Micheál Martin warned that "emergency measures will have to be taken quickly" in a worst-case no-deal Brexit and that "all bets are off" on what could happen next.
Speaking on the outskirts of the EU summit in Brussels before an ALDE European political umbrella group meeting, Mr Martin said the escalating crisis means serious questions are arising "on a number of fronts".
Noting an ESRI report which warned a no-deal Brexit will leave a €3.6bn black hole in the Irish economy next year, Mr Martin said a second emergency budget will be needed in 2019 to cope with the fallout.
"In the event of a no-deal Brexit all bets are off in terms of budgetary matters, in terms of emergency legislation, so clearly emergency measures would have to be taken on the Irish side quite quickly.
"I would think so [that an emergency second budget would be needed], quite definitely, you're looking at a hole in the budget in our exchequer figures if the review that was published is accurate, there would be very serious issues to arise. Hopefully we won't get to that, but we don't know," he said.
While the Government did not immediately respond to the emergency second budget demand last night, the call underlines the growing fears over the impact of a no-deal Brexit on State finances and businesses throughout the country.
At a recent Oireachtas budget oversight committee meeting, Irish Fiscal Advisory Council official Martina Lawless said while Brexit is likely to cut Ireland's GDP levels by 4%, a crash-out Brexit could see the downturn double to 8%.
The same issue was raised in the Dáil yesterday, with Fianna Fáil again calling on the Government to publish its Brexit worst-case scenario preparedness plans.
Speaking during leaders questions, Fianna Fáil deputy leader Dara Calleary said "the protracted internal politics in the UK means a no deal Brexit is moving closer every day".
Tánaiste Simon Coveney responded by saying a significant amount of work is taking place in the background to cope with all Brexit contingencies.
However, describing the lack of transparency as "pathetic" compared to the 70 plans published by the European Commission and 100 by the British government, Mr Calleary hit back.