The Government is under fire over its failure to outline detailed contingency plans for a no-deal Brexit - less than nine weeks from the deadline.
It comes after Europe Minister Helen McEntee made the extraordinary suggestion that the Government may not reveal arrangements for the cross- border trade until three weeks before the October 31 deadline.
Business Minister Heather Humphreys also warned businesses to prepare for the worst outcome, while still failing to set out the Government's plans.
There are mounting fears of a crash-out Brexit amid the escalating political crisis in the UK after prime minister Boris Johnson moved to suspend Parliament.
Fianna Fail business spokesman Robert Troy said: "It's as obvious as a nose on our face that Government needs to urgently step up our preparations for a no-deal Brexit. They can start by telling people exactly what their plan is."
Mr Troy said exporters had been "unable to get a straight answer" when they asked where the border checks would be if a no-deal came to pass.
"With only weeks left to D-Day, there remains far too high level of unpreparedness," he added.
There was further pressure from business lobby group Isme. Its chief executive, Neil McDonnell, said: "We really are into the eleventh hour", but added that he can't advise members on what will happen about customs and veterinary checks.
He said that if checks are to take place away from the border - as mooted in talks between the Government and the European Commission - "what does that look like and what do we need to do? If someone rings me up today and asks about it I can't say.
"The Government is going to have to start saying - quite soon - that we know that 'we have this in hand and we are going to announce plans'."
Mr McDonnell spoke out after ministers where challenged on the lack of details for business and border communities.
The Government has been in talks with the Commission about how to avoid border infrastructure while protecting the EU Single Market and Customs Union.
The solution on the table includes checks away from the border - at points of origin and destination like factories, farms and ports.
However, with just nine weeks to go to the deadline, little is publicly known about how such arrangements would work.
Ms McEntee said the Government was still working on the issue, and insisted: "We're not hiding anything."
She said the Government didn't have a "final outline" of how checks on the border would be avoided but added: "As soon as we do we will be giving that to people".
Speaking on RTE Radio, she could not say when this would be but added: "I think we'll be probably a lot clearer in four or five or six weeks".
Later Ms Humphreys was asked if this would allow businesses enough time to get ready.
She replied: "What we're saying to them is prepare for the worst possible outcome."
She reiterated the Government's intention to avoid a hard border and said ministers were in talks with the Commission to find "the best possible solution for Ireland".
Ms Humphreys added that "tariffs can be paid online" but there would have to be veterinary checks.
"We're talking to the European Commission. We're trying to find solutions. This is not easy," she said.
She added that the Government would continue to insist on the need for the backstop to avoid a hard border - which Mr Johnson wants scrapped - in any Brexit agreement.
"There will be no movement on the backstop. The backstop is our insurance policy and it will remain," she said.