Paris struck a deal with the Republic of Ireland to fast-track its commercial drivers crossing the Channel from Dover to the French port.
The agreement was made between Ireland’s Foreign Minister Simon Coveney and his French counterpart Jean-Yves Le Drian on Wednesday.
Mr Coveney said: “We’ve had quite detailed discussions in terms of differentiating Irish trucks from British trucks. Under the right circumstances Irish trucks will not need to be inspected, whereas UK trucks may need to be inspected.”
But the deal has angered haulage firms in the UK, who have blasted the EU for an apparent attempt to punish and humiliate Britain over Brexit.
Brexiteers were also doubtful the deal would work.
Richard Burnett, head of the Road Haulage Association, said: “This seems completely impractical to me, and is full of potential flaws. It appears ill-thought through.”
Dover MP Charlie Elphicke added: “It beggars belief that the Irish think they can have special access through Dover just because the French say so.”
Former first minister of Northern Ireland Lord Trimble also waded into the row and accused the Irish government of using Brexit negotiations as leverage to undermine the Good Friday Agreement.
Lord Trimble, who won the Nobel prize for his part in the peace process, accused Leo Varadkar of “riding roughshod” over the 1998 agreement.
He also claimed that Brexit could result in Northern Ireland ending up as part of an “effective EU protectorate”.
The news came after it emerged last night that Mrs May had given the nod to a fresh Brexit proposal she will present to Cabinet ministers next week in what some have called a fresh “stitch up”.
The plan is said to be a potential end to the Northern Ireland border riddle that has plagued Brexit negotiations since they began more than two years ago.
The new proposal would see the UK as a whole enter into a “bare bones” customs union with the EU until a future trade deal is negotiated.
But this would still see Northern Ireland shackled to EU rules and regulations, creating the divide down the Irish Sea that Mrs May has since been trying to avoid.
The deal is being ironed out by Mrs May’s EU advisor Olly Robbins.
Meanwhile, both No 10 and EU chief negotiator Michel Barnier denied a deal on financial services has been agreed on after the pound plunged by one percent due to the rumour.