Sainsbury’s boss Mike Coupe has issued a fresh warning over the impact of Brexit, claiming that “no solution” would replace the benefits of the customs union.

Coupe, who cautioned last September that fresh food imports could be left rotting at borders following the UK’s exit from the EU, said that falling out of the customs union would “compromise” food supply chains.

Roughly 30% of the groceries Sainsbury’s sells are imported from the EU and Coupe said that preventing the free movement of goods between nations would have a “material” impact on the business.

Coupe said: “Anything other than a customs union means that there is going to be some kind of delay, some kind of checking mechanism at borders.

“That either means that it adds cost to the supply chains that we run, or it means that the products we sell will be less fresh because they have to sit at ports.

“As far as I can see there is no solution which is better than the customs union and anything other than the customs union is a compromise, as far as the food supply chains that we operate are concerned.”

Coupe warned that a ‘hard’ Brexit would have even further-reaching consequences for retailers, claiming that “thousands” of lorries could be left queuing at borders.

“If there was a hard Brexit and somehow the drawbridge was pulled up, it wouldn’t take long before there were literally thousands of lorries parked on either side of the Channel,” Coupe cautioned.

“Given what we saw during the snow – it takes about three or four days for food supply chains to become disrupted – it would clearly be a big issue.”

Asked whether Sainsbury’s was making contingency plans for such a scenario, Coupe said: “We clearly have teams of people working on it, but until we know what the solution is, there’s not a lot we actually can do.

“During the next year, we will have to make choices about how and where we source products from, depending on how much clarity we get around the outcome [of Brexit talks].”