Taoiseach Leo Varadkar has warned that any departure by the UK government from last December’s agreement will make it very hard to strike a deal on Brexit.

He was responding to reports in the UK press that a push by Irish officials for a settled “legal text” over the Border question was threatening to derail Brexit negotiations.

Mr Varadkar said: “As far as I’m concerned, the joint report that was agreed in December contains commitments and guarantees. And those are the words used, ‘commitments’ and ‘guarantees’, and they are there in black and white. The UK government signed up to them and so did the EU.”

He added: “I’m sure they [the UK government] won’t want to renege on an agreement they only made a few months ago, and they would find it very hard to make any future agreement with Ireland, the European Union or anyone else in the world if they tried to depart from an agreement they made a few months ago.”

“I’ve every confidence that prime minister May and the UK government will stand by what they agreed.”

In mid-December, the Taoiseach said the agreeement, where the UK pledged to maintain full alignment with EU trade rules, provided a strong assurance against any hard border on the island of Ireland.

Meanwhile, Tánaiste Simon Coveney called on the British government to drop its red lines and tough talk on its future relationship with the EU.

Mr Coveney said a calm and rational debate on the merits of continued membership of extended customs union and single market structures was overdue.

Addressing a packed audience at a conference bringing together concerned business representatives on both sides of the Border, he warned the clock was ticking on a decision on what future trading relations will look like after Brexit.

The Tánaiste and foreign affairs minister told the event in Co Louth that the best interests of the UK, Ireland and the wider EU would be served by an arrangement as close as possible to the current free-flowing status quo.

“In our view this is best accomplished by the UK indicating that it wishes to be part of an extended single market and customs unions, allowing it to continue to access the world’s largest and most successful free market — a market British genius has helped design,” he said.

“Thus far, however, as we know, the British government has not been prepared to seek that type of relationship.

“My hope is that in the coming weeks, previous red lines and tough talking points will be put to one side, and a calm and rational debate about what is in the best interests of the people of Britain and Northern Ireland can prevail,” Mr Coveney said.

“That deliberation is overdue. And the clock is now ticking closer to the time when a decision on the future direction is needed.

“The closest possible customs and regulatory partnership is in the best interests of everybody, in my view, across these islands, and indeed in the best interests of the European Union and its future also.”

Mr Coveney said despite some media commentary on the phase one deal struck between the United Kingdom and the EU, there was no uncertainty over what had been agreed in relation to the alignment of regulations in key economic sectors on both sides of the Border after Brexit.

He said other EU nations remained “unstinting” in their support of Ireland’s stance on that issue.

British prime minister Theresa May’s inner Brexit “war cabinet” was meeting on Wednesday afternoon after it emerged the European Union wants a mechanism to punish the UK for breaches of any transition deal.

Stefaan De Rynck, an adviser to EU chief negotiator Michel Barnier, said sanctions for UK breaches of Brussels rules during the transition “of course” had to be part of any deal.

He tweeted: “The EU responds to PM May’s request to benefit from single market & customs union for a limited time during which all must play by the same rules. Foreseeing possibility of sanctions for foul play is of course part of any agreement.”–additional reporting PA