Taoiseach Leo Varadkar and EU Council President Donald Tusk have agreed to "intensify" preparations for a ‘no-deal’ Brexit.
Mr Varadkar and Mr Tusk spoke in a phone call this afternoon, following the announcement by British Prime Minister Theresa May that Tuesday’s House of Commons vote on the Brexit deal would be deferred.
They discussed the current situation on Brexit as well as this week’s European Council meeting, and agreed that preparations for a no-deal outcome should intensify.
They also agreed that the Withdrawal Agreement was the best option, and that it could not be renegotiated.
Mr Varadkar had earlier said that the Brexit Withdrawal Agreement, including the backstop, is the only deal on the table.
When asked if any changes could be made to the backstop, which is designed to avoid a hard border on the island of Ireland post-Brexit, Mr Varadkar said a lot of concessions have been made along the way.
"I have no difficulty with statements that clarify what's in the Withdrawal Agreement but no statement of clarification can contradict what's in the Withdrawal Agreement," Mr Varadkar added when asked if the Government would support a statement from the EU clarifying issues around the Irish backstop.
A Government spokesperson has said there at no plans for the British Prime Minister to visit Ireland in the coming days.
Ms May has said that she will visit EU leaders to seek assurances over the Irish backstop.
Earlier, Tánaiste and Minister for Foreign Affairs Simon Coveney said the legal text of the withdrawal agreement will not change.
He said the deal was a "hard-won compromise" that was fair to both the EU and Britain and would not be re-negotiated.
"The deal ... is not going to change. Particularly the legal language of the withdrawal treaty. I hope people will see it for what it is, which is a fair, balanced document," he said in Brussels.
The European Union's executive said it would not renegotiate its Brexit agreement with Mrs May.
"We have an agreement on the table," a spokeswoman for the European Commission told reporters, recalling a position expressed by President Jean-Claude Juncker.
"We will not renegotiate."
The spokeswoman said the bloc was ready for "all scenarios" and added that Mr Juncker spoke by phone with Mrs May yesterday.
The Taoiseach spoke to Mrs May yesterday evening also, and discussed the current situation on Brexit as well as this week's European Council meeting in Brussels.
Elsewhere, former British prime minister John Major has launched a scathing attack on what he described as the "breathtaking" ignorance of the so-called unionists who are opposed to the backstop in the Brexit deal.
Mr Major has warned about the dangers of violence returning if a hard border is ever restored.
Mr Major said that despite the turmoil and the decision taken this afternoon to defer the vote in the House of Commons, he still expected common sense to prevail.
He said he fully anticipated that a majority of MP's in the House of Commons would eventually vote in favour of a soft Brexit.
He warned people who had forgotten about the troubles that the first people to lose their lives on the border were customs officers.
He said nobody wanted to go back to those days and it was in the economic interests of Britain and Ireland to ensure there was not a hard Brexit.
Mr Major was speaking at the inaugural Albert Reynolds Memorial lecture in Co Longford, which is on the week of the 25th anniversary of the Downing Street declaration.
Additional reporting Ciaran Mullooly