The Tánaiste Simon Coveney has warned the chances of a disorderly Brexit in the UK "have never been higher".
He says the Government now considers the risk of this happening on October 31st as "significant".
Writing an editorial for the Irish Times, Mr Coveney says he will bring a detailed update to Cabinet on Tuesday on contingency planning across all Government departments and State agencies.
"It refines and improves on all the actions that were already in place for the March 29th and April 12th Brexit deadlines", he says, adding that this will continue to be prioritised in the weeks ahead.
He has also re-stated Ireland's commitment to the backstop, and hit out at inaccurate commentary in the UK during the Conservative Party leadership race.
"In recent weeks we have observed and listened to some inaccurate utterances about ourselves, the EU and the backstop.
"Of course people can have their own opinions, but they cannot have their own facts.
"The facts are that Brexit is a British decision, triggering article 50 on March 29th, 2017, was a British decision, and the red lines laid down for the negotiation are British red lines", Mr Coveney says.
Calling the withdrawal agreement a "hard-won deal", he says: "It recognises the uniqueness of Northern Ireland. It is an insurance policy and we hope it doesn't need to be used.
"But the backstop gives us certainty now, certainty that is essential to protect stability on this island.
"Any other arrangements agreed in the future must deliver the same outcome."
Mr Coveney says one of the biggest threats to Ireland is the 'boy who cried wolf' effect - where people assume because no-deal was avoided in March and April that it will happen again in October.
"To assume this would be a serious error", he warns.
Most of the emergency legislation needed for no-deal has already been passed by the Dáil.
But as it prepares to enter the summer recess after this week, and with a new British prime minister about to be elected, this is a clear message from the Government that Ireland's position is not up for re-negotiation.