Taoiseach Leo Varadkar has revealed checks may be required on the Irish border in the event of a No Deal Brexit.
Mr. Varadkar made the comment during a speech to business leaders in Dublin on Thursday evening.
The Fine Gael leader said checks would be needed for goods and live animals and added that the checks would take place "as far as possible" in ports, airports and businesses.
"But some may need to take place near the border," said Mr. Varadkar.
Mr. Varadkar repeated his view that there is nothing to be gained by the U.K. leaving the E.U. without a deal.
"We don't wish to see a no-deal Brexit and we will continue our efforts to avoid one, but not at any cost.
"Unlike some, I see no upsides to no-deal. I do fear it. But I am prepared for it."
The Taoiseach told a British Irish Chamber of Commerce dinner that his government is "working out the details" with the European Commission in terms of the impact of a no-deal Brexit.
"There will still be plenty of food on shelves but perhaps not all of the same brands," he said.
"When you fly into Ireland from Britain, you will no longer pass through the blue channel.
"You will have to choose the green or red one and pay any taxes that may be due.
"The same will apply to products bought online from the UK, brought in from Northern Ireland, and EU consumer protections will no longer apply.
"Flights, trains and buses will continue to operate normally for a period but an agreement will be needed for this to continue permanently. EU vessels will no longer be allowed to fish in UK waters and vice versa, though the Commission has proposed a short extension of the status quo.
"Tariffs will apply to goods imported into Ireland from the United Kingdom and vice versa.
"There will be checks on goods and live animals and, as far as possible, they will take place in ports, airports and at businesses. But some may need to take place near the border.
"We are working out the details of this with the European Commission."
Mr. Varadkar did however end his speech on a positive note by saying that regardless of what happens the U.K. will continue to be a "vital trading power" for the South.
"The UK is geographically and culturally our closest neighbour and will continue to be a vital trading partner, no matter what shape Brexit takes," he said.