Ireland's deputy prime minister has said checks on Irish goods in EU ports "is not a runner".
Tánaiste Simon Coveney said Ireland cannot allow a no deal which drags Ireland out of the single market.
Mr Coveney said he agreed with Michel Barnier, the EU's chief Brexit negotiator, that as the days pass a no deal Brexit looks "a very real possibility".
He told the Irish parliament (the Dáil) that Ireland must prepare for no deal.
Mr Coveney said he would bring two papers to cabinet on Tuesday evening, when the Taoiseach Leo Varadkar returns from his meeting with the French President, Emanuel Macron.
The Tánaiste said the Irish government had a dual responsibility and a difficult protecting the European Single market and the Good Friday Agreement peace process.
"Ireland is not going to allow a situation where the UK leaving the European Union without a deal drags Ireland out of the single market with it. We cannot allow that. And what I mean by that is the response being checks on EU ports on all Irish products, that is not a runner," he said.
He added the Irish government is working on a plan to make sure it fulfils its dual responsibilities.
Meanwhile, Fianna Fáil spokesperson on Brexit Lisa Chambers TD said the government must be open and transparent with the Dáil and with the Irish public about how they plan to "protect the integrity of the single market and the customs union" whilst avoiding a hard border on the island of Ireland.
"To date, the government has been evasive when pressed on this issue and we are learning more about what is actually going on from EU officials rather than hearing it directly from our own government," she said.
"The issue of the border affects every citizen on this island and the Taoiseach and the Tánaiste must be more forthcoming about what will actually happen in the event of a no deal Brexit."