Tánaiste and Minister for Foreign Affairs Simon Coveney has said that a no-deal Brexit was an "ugly prospect".
He was speaking after the Government published its latest update on preparations for Britain's plans to leave the European Union.
Mr Coveney said he believed that a hard Brexit will put a great deal of strain on political relationships on the island of Ireland.
He warned that it would also be a "fundamental disruptor" to the all-island economy.
In the contingency action plan, the Government said that north-south trade would be particularly affected in the event of a hard Brexit, and that it could no longer be as frictionless as it is today.
The impact of tariffs, customs and associated checks would involve additional costs and disruption for businesses, the report states.
Without the Withdrawal Agreement and the backstop there are no easy answers but work is under way to minimise these consequences of no-deal but any arrangements would be sub-optimal, the document states.
Engagement between Ireland and the European Commission is continuing in an effort to deliver the shared twin objectives of avoiding a hard border and maintaining the integrity of the Single Market and Customs Union.
The report said that a hard Brexit would have "profound" economic implications for Ireland on "all levels".
It says that it will be impossible for the UK to maintain its current "seamless arrangements" with Europe across justice, security, transport, trade flows and supply chains.
The plan also acknowledges there is a "high degree of uncertainty" about forecasting the impact on Ireland.
But it adds the impacts in the first year following a no-deal would be "very damaging".
It says small and medium businesses and companies in the regions would suffer "severe negative effects".
It adds the impact of UK import and export exposure for firms could be compounded by currency volatility between the euro and sterling and it repeats that there would be an expected increase in unemployment of 50-55,000 after the UK leaves.
The Government said that tariffs, checks and controls on UK imports will be disruptive to trade across the Irish Sea.
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It also said the UK land bridge (where vehicles travel from Ireland across the UK to get to Europe) would be subject to severe delays, and adds there would be disruption to the all-Ireland economy.
The Government will make commitments to the people of Northern Ireland to ensure that students have access to the Erasmus programme, and Northern Ireland citizens can use European Health Insurance Cards.
It said a new phase of the Brexit communications will be rolled out, which will include a call to action to business operating in exposed sectors to make preparations for a no-deal.
It will also provide additional infrastructure at ports and airports to enhance capacity.
Earlier, the Government described as incorrect media reports that it has accepted the need for checks close to the border with Northern Ireland in the event of a no-deal Brexit.
It followed a report by Bloomberg which said that "Ireland is set to acknowledge publicly for the first time the need to set up checks at or around its border with Northern Ireland in a no-deal Brexit scenario, people familiar with the matter said".
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The Tánaiste said that since the six-month extension was granted at the end of March, "some people I think had focused so intensively on Brexit that they took their foot off the accelerator and that needs to end now.
"We need to get the country collectively ready for all potential Brexit outcomes."
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The Government's contingency plans were due to be presented to opposition parties, after they were presented to Cabinet.
Sinn Féin leader Mary Lou McDonald said the Government is correct to put a renewed focus on the possibility of a disorderly Brexit and the Government must lead from the front and say that if the UK chooses to crash our of the EU, that decision cannot mean that Ireland takes a step backwards.
Fianna Fáil's Brexit spokesperson Lisa Chambers said there must be a renewed energy and focus at the heart of Government.
She said it is a little incredible to tell citizens that we do not have a plan for checks on food and goods with just over 100 days to go until the 31 October deadline.
Additional reporting David Murphy, Laura Hogan
