Justice Minister Charlie Flanagan has insisted the State will be properly policed, whatever the outcome of Brexit.
Mr Flanagan was attacked by the Opposition for failing to reveal how many extra gardaí will be deployed in border counties as the likelihood of a no-deal Brexit increases.
With little hope of British Prime Minister Theresa May's plan making it through the House of Commons, Dublin has come under increasing pressure to publish its no deal contingency plans, but has refused to do so.
Tanaiste Simon Coveney has repeatedly insisted Ireland is not preparing for a no-deal, but other Government sources say otherwise, insisting Mr Coveney's office has ordered silence on the matter.
Mr Flanagan said that in terms of policing the border, new Garda Commissioner Drew Harris has been given an unprecedented budget of €1.7bn for 2019 to deal with whatever scenario unfolds.
“Simon Coveney and his team have been engaged in contingency planning over a wide range of issues. The issue of a hard border between Northern Ireland and Ireland simply doesn't arise. If you are talking about a heavily fortified border, as we had in the past, that simply does not arise.
"Everyone has said that will not happen.
"That will not arise,” he said.
Fianna Fail's Jim O'Callaghan called on Mr Flanagan to set out what the Government's plans are in the event of no deal.
“In the possibility of a no deal, there is a hard border in Ireland. No one wants it but there are going to be customs checks and if there are customs checks there is going to be smuggling, and if there is smuggling there has to be policing.
"We should be hearing a number of what gardaí will be needed. We have heard there will be 600 more customs officers, we have heard the PSNI will hire 400 more officers in terms of Northern Ireland. We need to hear the Government's contingency plan for a hard border. It is a serious possibility.We need a plan,” he said.
Fine Gael Senator Neale Richmond hit back at Mr O'Callaghan for “recklessly” talking up the worst case Brexit scenario by demanding extra contingency planning for a hard border.
“For the past two and a half years, the Government has been working with its European partners to guarantee there is no hardening of the border on the island of Ireland post Brexit.
“There is widespread recognition across the EU and in the UK that any material hardening of the border would be a breach of the Good Friday Agreement.
"Neither the European or British sides in the Brexit talks envisage such a hardening and they have hammered out a deal that ensures that, through an ambitious future relationship underpinned by a backstop insurance policy.
“It is absolutely reckless therefore to hear a senior Fianna Fáil spokesman undermine this ratification process with calls of additional customs and policing allocations for the border,” Mr Richmond said.
Meanwhile, Former US Secretary of State John Kerry has warned it is "imperative" to resolve the issues thrown up by Brexit surrounding the Irish border in a way that does not reignite the Troubles.
Mr Kerry made his comments during an event in the United States to mark the 20th anniversary of the Good Friday Agreement.
He told the BBC's Sunday Politics programme that a hard border between Northern Ireland and Ireland could "re-heat passions".
Mr Kerry was joined by politicians from Northern Ireland's five main parties at Yale University.
"Under the Stormont Agreement, the last 20 years have been characterised by a border which people have been able to cross easily," he said.
"If you have a certain kind of Brexit with a hard border you could see great difficulties emerge as a consequence of that.
"I have concerns that depending on what kind of Brexit takes place it could have a negative impact on the progress made in the last 20 years.
"It's imperative that it's resolved in a way that it does not reignite the Troubles."
The Democrat stressed his meeting with Northern Ireland's parties was not a negotiation, describing it instead as an "informal meeting".
"It's an academic meeting at a university where the parties came to be able to explore their dynamics and to have a candid, out of the spotlight, frank conversation with people who know something about the issue and care about the issue," he added.