Marks and Spencer has said it is cutting Christmas products sent to Northern Ireland over fears about post-Brexit customs checks.
It comes ahead of Britain’s expected warning to the EU that, without a simplified deal, it will override the arrangements.
Chairman Archie Norman predicted “gaps on shelves” once border checks come into force in September.
“This Christmas […] we’re having to make decisions to delist product for Northern Ireland because it’s simply not worth the risk of trying to get it through,” he told the BBC.
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“We’re waiting to see how serious it’s going to be but if it’s anything like southern Ireland, and at the moment it’s set to be, then it’s going to be very, very serious for customers.”
Marks and Spencer employs 14 vets “ticking boxes and filling out forms” to certify exports to the Republic of Ireland, where the checks are already in place.
It has stopped exporting half its sandwich range, which need three veterinary certificates.
Norman added the arrangements were “very threatening” to the supermarket, which operated throughout the Troubles.
In a letter to Brexit minister Lord Frost, he said the EU and UK should set up a “trusted trader” scheme and overlook the “trivial” paperwork errors that have caused delays.
“Any scheme should start on the basis that we are prepared to follow EU standards for products going to Northern Ireland,” he continued.
However, the government has consistently refused concede control over food standards.
Number 10 said Mr Norman’s letter was a “stark warning” of “the fundamental problems” with EU border checks.
“That is why we need to urgently tackle these issues, to ensure there is minimal disruption to people’s lives in Northern Ireland” it added.