Taoiseach Leo Varadkar has warned British prime minister Theresa May "there isn't much time left" to agree a workable Brexit just a week out from a crucial European Council summit meeting.
Speaking at Government Buildings alongside European Commission president Jean Claude Juncker, Mr Varadkar said the reality is Britain has yet to resolve the Irish border stand-off and that nothing will happen until this is addressed.
In recent weeks the planned June European Council summit deadline for Britain to provide a clear Brexit plan has effectively been pushed out until the next summit in October.
However, Mr Varadkar said on Thursday morning that time is running out for Britain to address the matter.
"At our meeting [between Mr Varadkar and Mr Juncker] we were in full agreement that there is now an urgent need to intensify our efforts if we're to get there.
"We'll be discussing this further at the European Council meeting next week and our EU partners are absolutely steadfast in their backing for us," Mr Varadkar said.
The Taoiseach also said despite suggestions from hard-line Brexiteers "it's abundantly clear that for there to be a withdrawal agreement there has to be full agreement on all issues".
He said in December Britain gave the EU "a cast-iron guarantee of no hard border on the island of Ireland, no physical infrastructure and no associated controls or checks", and said this must be honoured.
Asked about the Irish focus on the backstop over the Irish border, Mr Varadkar said "a withdrawal agreement without the backstop is of no use whatsoever" and that "a backstop cannot have an expiry date".
Speaking at the same press conference before attending a join Dáil and Seanad debate on Brexit, European Council president Jean Claude Juncker insisted the Irish border stand-off "is not a bilateral question between Ireland and the United Kingdom".
Noting the fact some members of the European Parliament have suggested Brussels should step back from the issue and concentrate on wider Brexit matters, Mr Juncker said this will not happen.
"Sometimes in the European Parliament, some of the members there say that this is not our business that this is a bilateral between Ireland and the UK.
Today's meetings were also attended by chief EU Brexit negotiator Michel Barnier, Tánaiste Simon Coveney and European Affairs Minister Helen McEntee.