Leo Varadkar urged Jeremy Corbyn to show leadership as he indicates Brussels is receptive to further delaying Brexit
The taoiseach believes the European Council would be open to further delaying Brexit but insisted such a move could not be "a licence for further indecision" from the British government.
Leo Varadkar told the Dáil that the British government needed a clear plan if it was to secure an extension to Article 50 past the end of next week.
"My general sense across the European Council is that it is open to granting a further extension to the United Kingdom, but we don't want that further extension to merely be a licence for further indecision," he said.
"We need a decision from the United Kingdom government and parliament – we need a clear plan."
The Fine Gael leader warned that there was a "real concern" that if the UK remained in the EU past May 22 but did not hold elections, then it could risk the European Parliament not being properly constituted.
Mr Varadkar said he was hopeful Jeremy Corbyn would show leadership and come up with a compromised Brexit plan with Theresa May.
He described the Tory leader's engagement with the Labour leader on Brexit as "timely".
"I don't know if Mr Corbyn will rise to the occasion, whether he will show leadership and be able to come up with a compromised plan with Prime Minister May – I hope he does, but we will see if that happens in the next couple of days," the taoiseach said.
He also stressed that the backstop would ensure the border between Northern Ireland and the Republic would be "tariff free, friction-fee, quota-free and bureaucracy-free".
"I don't know for certain that it's possible to come up with an alternative that does that other than the UK remaining in the EU or staying in the single market and customs union, but we will do everything we possibly can to avoid the emergence of a hard border" he said.
"We know that some things can be done remotely, like the collection of tariffs and customs duties."
Earlier, Tánaiste and Minister for Foreign Affairs Simon Coveney welcomed developments in London and said it was very unlikely the UK would crash out of the EU next week.
Speaking to RTÉ, Mr Coveney said Dublin would support the UK if it sought a short extension.