Fianna Fáil is accusing the Government of ‘overselling’ commitments made by the UK on the Irish border.

The Taoiseach has claimed that the Phase One Brexit agreement provides a “rock solid and cast iron” guarantee that there will be no return to a hard border.

Leo Varadkar said the commitment included a “back-stop arrangement” whereby, if all else fails, Northern Ireland would “maintain full alignment with the rules of the internal market and customs union which are relevant to the avoidance of a border, North-South cooperation and the all-island economy.”

The Government has called for the commitment to be included in a legally binding Phase One agreement, however chief EU negotiator Michel Barnier this week indicated that this may not now happen.

On Newstalk’s On the Record this morning, Fianna Fáil’s Brexit spokesperson Stephen said the Government “probably oversold this in December.”

“The problem is this,” he said.

“In the last few days it would appear that Barnier’s team has decided to take the legal text for that back-stop out of the withdrawal agreement and stick it in a different document called the protocol,” he said.

“Certainly, regardless of the nuanced legal opinion on protocols versus withdrawal agreements, what has happened is a political fudge.

“Our fear is that it is backsliding and that it is putting less strength on this back-stop.

“People I am talking to in Brussels are saying, ‘look this is political fudge, they are trying to create space to allow the talks to move forward’ – and of the course the talks do have to move forward.

“But they cannot under any circumstances move forward at the risk of border controls in Ireland.”

The DUP has indicated it will not accept any arrangement that results in the North facing different regulations to Britain – while the British Prime Minister Theresa May has so far rule out entering any form of customs union with the EU after Brexit.

On Friday, the Taoiseach urged the UK Government to provide "real detail" on its Brexit position, as he arrived at an EU summit in Brussels.

Speaking at the same summit, the European Council president described the UK position as “pure illusion.”

Up till now, Mrs has faced no opposition in the UK to her refusal to enter a customs union, however this afternoon the Labour Party confirmed it now supported a union following Brexit.

The party's shadow Brexit secretary Sir Keir Starmer confirmed Labour want a new treaty with Brussels that "will do the work" of the UK's current membership of the EU's customs union.

The party’s leader Jeremy Corbyn will announce the shift in Labour's Brexit policy during a speech on Monday, following "many weeks of discussion" within the party, Sir Keir added.

The move will pile pressure on the Prime Minister, with Sir Keir suggesting Labour could now back an attempt by Tory rebels to force the Government into agreeing a similar position.

Sir Keir claimed Labour had "long championed being in a customs union with the EU and the benefits of that."

"It's really important for our manufacturing base and nobody can answer the question how you keep your commitment to no hard border in Northern Ireland without a customs union," he told the BBC's Andrew Marr Show.

Sir Keir said Labour had "unanimously" agreed at a meeting last week to "develop" their Brexit policy.

He said: "It's a customs union… there's going to have to be a new agreement, but will it do the work of the current customs union? Yes, that's the intention."

Sir Keir admitted Labour's position means it will have to be "negotiated" as to who is in control of Britain's trade policy after Brexit.

He said: "We will have to have a say but the real point is - because we all want trade agreements, we all want more trade agreements - are we more likely to get them if we do it jointly with the EU or on our own?

"All the evidence suggests more likely if we do it with the EU and the cost-benefit analysis of coming out of the customs union and having new trade agreements just isn't borne out."

Tory Remainer Anna Soubry has tabled a cross-party amendment to the Trade Bill in an attempt to compel the Government to retain a customs union with the EU after leaving the bloc.

Heightening the prospect of a parliamentary defeat on the issue for Mrs May, Sir Keir suggested Labour could back Ms Soubry's move.