Tánaiste Simon Coveney has said Brexit talks must intensify over the summer, particularly on the border issue, or Britain risks being unable to withdraw smoothly from the European Union.
"We had asked for and looked for significant progress in June. The British government have been unable to deliver on that," he said.
"That is frustrating for everybody but if anything the negotiations need to intensify, particularly on the Irish backstop element of the withdrawal agreement."
Speaking on RTÉ's Morning Ireland, Mr Coveney added: "But let's be very clear, there will be no withdrawal agreement, no transition agreement and no managed Brexit if the British government do not follow through on their clear commitments in writing to Ireland and the whole EU."
He said the prospect of a no-deal scenario was being contemplated within the EU and that the negotiations had increased the solidarity between Ireland and the other EU countries.
"We have been reassured over and over again that Ireland will not be left isolated here."
Mr Coveney said the uncertainty was set to continue for now for people in the border counties.
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He said the prospect of a no-deal scenario was being contemplated within the EU. "This is a question many people are asking," he said.
Mr Coveney and Taoiseach Leo Varadkar met European Commission President Jean-Claude Juncker at Government Buildings to discuss the Brexit negotiations.
Sinn Féin leader Mary Lou McDonald said the UK government's view on Brexit was a policy of "Ireland last, if at all".
She met British Prime Minister Theresa May yesterday and said Mrs May was "well aware of the fact that Brexit and the Good Friday Agreement are mutually incompatible".
Speaking on RTÉ's Today with Sean O'Rourke, Ms McDonald said the British government was playing games and "running down the clock" in the hope that it would give the UK an advantage by autumn as it pursues a future relationship with the EU.
She said at the heart of this is a failure by the British government to accept that Ireland's circumstances are unique and exceptional and require a focused look.
Ms McDonald added that she would like to hear from Mr Junker today that the previously stated position of June as a critical deadline for agreement on the Irish border remains the EU position.