Dublin has signalled support for extending the UK’s Brexit transition period in order to resolve Irish border issues.

The country’s deputy prime minister Simon Coveney reacted positively to reports that EU chief negotiator Michel Barnier was open to pushing the implementation period back a year to end in December 2021.

However, Government sources insisted Downing Street was not calling for an extension to transition arrangements as Theresa May prepares to address EU leaders as she battles to keep her faltering hopes of securing a Brexit deal alive.

The Prime Minister travels to Brussels for what had been billed as “the moment of truth” in the negotiations amid growing concerns the two sides will be unable to bridge the gap over the key issue of agreeing a “backstop” deal to ensure there will not be a return to a hard border in Ireland when the UK quits the EU.

Mr Coveney told BBC Radio 4’s Today programme: “What Michel Barnier is now suggesting is, look, let’s ensure that the backstop is never likely to be used by creating the space and time for the UK and the EU to be able to negotiate UK-wide customs arrangements that can ensure that there won’t ever be the need for customs checks between Britain and Northern Ireland.

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Countryside near Castlederg, Co Tyrone, part of a former smuggling route covering both sides of the Irish border (Michael McHugh/PA)

“We have always said that we are happy to show flexibility in terms of how we get to a destination where-by there is a backstop, or an insurance mechanism, in place to reassure people on the island of Ireland that they are not going to see the re-emergence of physical border infrastructure.

“And what Michel Barnier has indicated very clearly is that the EU side, certainly, is willing to allow more time in the transition period to agree an alternative solution to a backstop.”

The EU meeting is the occasion when the leaders of the remaining 27 member states were supposed to give the green light for a special summit in November to finalise the terms of Britain’s withdrawal.

But Mr Coveney made it clear that summit would not go ahead unless significant progress is made on the border issue.

He said: “I think what’s more likely is that dates will be suggested, but that there won’t be a commitment to a new summit unless there is a signal from the negotiating teams that there is something to sign off on.

“Both sides want to get a deal done here, and I think we need… to allow the negotiating teams to set the pace with a view to making recommendations, hopefully by mid-November, that a new summit is necessary to sign off on a final deal.”

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Donald Tusk has warned there can be no progress without new proposals from the UK (Niall Carson/PA)

European Council president Donald Tusk has warned that without new “concrete proposals” from the British to break the logjam over the Irish border backstop, further progress on a deal may be impossible.

However, with her party split, and some Tory MPs openly calling for her to go, Mrs May has little room to manoeuvre if she is to secure a deal which stands any chance of getting through Parliament.

Ahead of her visit to Brussels, Mrs May was able to secure the backing of her Cabinet, at least for now, amid reports that some Brexiteer ministers were prepared to quit if she gave too much ground to Brussels.

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(PA Graphics)

However, there was anger among Tory Brexiteers after The Daily Telegraph reported that Chancellor Philip Hammond warned the meeting that the UK could still have to pay the EU up to £36 billion of the £39 billion “divorce bill” to settle its outstanding liabilities, in the event of a no-deal break.

The Prime Minister will briefly address the leaders of the EU 27 on Wednesday evening before they discuss the state of play in the Brexit negotiations over a working dinner while she leaves.

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Michel Barnier has said he will work calmly and seriously to reach a deal (Niall Carson/PA)

Mrs May will also have bilateral meetings with European Commission president Jean-Claude Juncker, European Council president Donald Tusk, and Irish Taoiseach Leo Varadkar.