The British Labour Party is seeking to build a cross-party agreement to enshrine in law a promise by Britain that there will be no hard border in Ireland after Brexit.
The plan to amend Brexit legislation would force the British government to honour previous commitments to avoid visible border checks when the UK leaves the European Union next year.
Any move to introduce laws that would ‘bind’ the UK to it commitments could cause a further headache for Theresa May, whose party has a slim Westminster majority propped up by the DUP.
Shadow Brexit secretary Keir Starmer has suggested his party now wants to ensure that previous commitments are firmed up in law.
“At the end of last year, the EU and UK government made a political agreement that there would be no hard border in Northern Ireland,” he said.
“However, the content of the withdrawal agreement is not legally binding.
“It is a political document subject to negotiation and will not have legal force unless and until it is ratified – which is by no means a done deal,” he told The Observer.
British government officials claimed over the weekend that a border agreement will be found.
Brexit Secretary David Davis has insisted that a solution will be found to the border issue after Brexit and a trade deal with Brussels is now "incredibly probable".
The Brexit Secretary said a trade deal - "the most comprehensive one ever" - would make the border problem much easier to solve.
Mr Davis said the British government was committed to protecting the Good Friday Agreement "at all costs".
"There is a risk in trying to focus just on the downsides because the real likely outcome - the overwhelmingly likely outcome - is option A," he told BBC's Andrew Marr show.
"Option A is that we get a free-trade agreement, we get a customs agreement, all of those make the Northern Ireland issue much, much easier to solve."
The EU withdrawal deal includes a fallback option of the north effectively continuing to remain in the customs union, but Mr Davis said either the UK-EU trade deal or new technology could prevent that.
When challenged that there were no other borders of that kind in the world, Mr Davis said: "We have got a whole load of new technology now."
"There are ways to do this, you can't just say 'we haven't done it anywhere else', we haven't attempted to do it anywhere else."
Pressed on Labour's planned amendment to Brexit legislation - which would enshrine the commitment to no hard border in law - Mr Davis said he would have to see what they came up with.
"We will not allow a return to the borders of the past, we will preserve - at all costs - the Belfast Agreement."
Meanwhile, former shadow secretary of state Owen Smith has said he "stood by his principles" in calling for another EU referendum in an article in the Guardian newspaper.
The move resulted in him being sacked from Labour's shadow cabinet by Jeremy Corbyn last week.
"I think it is a mistake, for Jeremy Corbyn in particular, who has always understood the value of people standing by their principles,” he said.
"It is the position that he has often adopted, and it is certainly a value in him that others have extolled."
"In truth I think that is all I have done. I have stood by my principles," he told BBC Radio 4’s Today programme
