Updated 3.55pm

TAOISEACH LEO VARADKAR said today that the government will need to “seriously ask” whether a withdrawal agreement is possible at all if there is no significant progress by June on the “backstop’’ in the Brexit treaty that guarantees no hard border in Ireland.

Varadkar was commenting after the Daily Telegraph reported that the European Union has roundly rejected proposals from the British government for avoiding a hard border between Ireland and Northern Ireland.

EU sources told the Telegraph that Prime Minister Theresa May’s plans were subjected to a “systematic and forensic annihilation” at a meeting between senior figures on both sides this week.

The Telegraph’s source is quoted as saying that it was made clear that “none of the UK’s customs options will work”, as part of a “detailed and forensic rebuttal”.

Varadkar said today that the Irish government is “open to alternative proposals that may come from the United Kingdom” but that, so far, “they haven’t been forthcoming”.

Prime Minister May has been clear in her plans for the UK to leave the single market and customs union but, in December, the British government offered a guarantee that this would not mean a hard border on the island of Ireland.

Tánaiste Simon Coveney would not comment explicitly on the leak in today’s Telegraph, saying that the Irish government does its talking through the EU taskforce and through regular private contact with the British government.

Speaking in Cork today, he said that Ireland’s position is “rock solid and consistent” and that he is “confident” that negotiations will be able to end with no hard border while protecting Ireland’s close relationship with Britain and the island’s internal market.

What is being dubbed as the “penny dropping” moment for the UK is widely seen as the EU taskforce and the other member states standing behind Ireland and it’s position on the border.

The Irish government has repeatedly taken the stance of – if the UK wants to sever trade ties with the EU in this way – the onus is on the British to find a solution for the border.

There are three ways this could happen: either the UK actually retains membership of the single market and customs union (which May has always ruled out), some kind of technological solutions are found to address the specific problems in Ireland, or that Northern Ireland remains part of the single market while the rest of the UK leaves.

The last choice is unpalatable to many UK politicians, particularly the DUP whose support is keeping May’s Conservatives in government.

That leaves the second option which would allow the UK to set its own tariffs on trade while avoiding a hard border, and it is proposals on these solutions that are reported to have been roundly dismissed by the EU this week.

The Telegraph reported that two proposals were given. The first, dubbed a “customs partnership” would have seen the UK set its own system of tariffs on goods entering it, but also act as a collector of EU customs duties on goods that enter the UK bound for an EU country.

As this would put the onus on businesses to collect the tariffs – in lieu of a border check collecting it – the EU rejected it. It was also rejected as the EU would not allow a country outside its supervision mechanisms to level duties on goods, and implementing the scheme would be too expensive.

The other option was rejected by the EU as a “turning a blind eye” approach.

The “customs arrangement” would have seen technological and administrative measures ensuring trade with the EU remaining frictionless. In the specific case of Northern Ireland, it would have allowed traders to operate across the border without any checks.

Writing in The Irish Times today, Coveney said there are five rounds of negotiations between now and June for the British government to follow through on their political commitments given last December and March and to reach agreement with the EU taskforce.

“I was very clear in London that Ireland needed to see definitive progress by June. If not, it will be difficult for the negotiations to proceed as before,” the Tánaiste stated in the article.

May is under pressure in the House of Commons from a group of MPs seeking to keep the UK in the customs union. This would remove the possibility of a hard border in Northern Ireland, but it is opposed by hardline Conservative MPs.

This will be debated in Westminster next Thursday. While any vote is not binding, any loss for the government will heap further pressure on its current Brexit strategy.

Time is running out for a border found, with the UK due to leave the EU in less than a year, and everything needing to be agreed by roughly October of this year.

Additional reporting by Christina Finn