Theresa May will put herself on a collision course with Dublin this week by insisting on a post-Brexit trading border between Northern Ireland and the Republic.
A crucial “position paper” is expected to stick to Britain’s current plan to use smart technology and spot checks to police the flow of goods between the two countries after 2019.
The stance will anger the Irish Government, which fears the impact on the peace process in the North and has pushed for the Irish Sea to become the post-Brexit border with the UK instead.
In recent weeks, the Taoiseach has made plain his growing frustration with Britain’s failure to come up with workable proposals in the 14 months since last year’s EU referendum.
A failure to reach agreement on the Irish border will also throw into jeopardy the Prime Minister’s hopes of an autumn start to talks on post-Brexit trade with the EU.
Brussels has insisted sufficient progress must be made on Northern Ireland, citizens’ rights and the so-called “divorce bill” before the negotiations can move forward.
Nevertheless, the formal position paper is not expected to give ground and will also play for time by arguing the border issue can only be resolved once the shape of a future trading deal is known.
At least three documents will be published this week, as ministers seek to rebut widespread criticism that Britain’s aims for the negotiations are a muddle.
Another paper will set out how to ensure “continuity in the availability of goods”, addressing the vexed issue of future customs arrangements.
And a third will explore “confidentiality and access to official documents following the UK’s withdrawal”, the Department for Exiting the European Union (DExEU) said.
The publications will show that “intense work is underway to prepare for formal talks on the future, deep and special partnership the UK wants to strike with the EU”, a source at the department argued.
Brexit Secretary David Davis, said: “Over the last year, the Government has been working with British businesses and the British people to establish exactly how our new relationship with the EU should look and feel.
“And over the coming weeks we’ll advance that thinking with a swathe of new future partnership papers.
“I’ve launched this process because with time of the essence, we need to get on with negotiating the bigger issues around our future partnership to ensure we get a deal that delivers a strong UK and a strong EU.”
The Government will hope the position papers will convince the EU Commission that it does have a coherent plan, when the exit talks resume at the end of this month.
After the last round of negotiations, Michel Barnier, the EU’s chief negotiator, was highly critical of Britain’s lack of preparedness, as he announced there had been no breakthrough.
The Cabinet has been accused of “negotiating with itself”, reflecting stark divisions over whether to pursue a lengthy transition period to avert the economic damage of crashing out of the EU with no agreement.