The head of Sainsbury's has warned fresh food could be left rotting at the British border if strict customs controls for EU goods come into force.
Wading directly into the Brexit debate, Mike Coupe said anything disrupting established food supply chains, currently governed by EU customs arrangements, would be "detrimental".
"The UK sources roughly a third of its food from the European Union and food is by far and away the UK's largest export," Mr Coupe said.
"If you take our fresh produce supply chains, for example, we put things on a lorry in Spain and it will arrive in a distribution centre somewhere in England, and it won't have gone through any border checks.
"Anything that encumbers that has two effects: it adds cost, and it also has a detrimental effect on freshness - if you're shipping fresh produce from a long distance, even a few hours of delay can make a material impact."
Last week, the British Retail Consortium said that food prices, which have already soared after the collapse in the pound post-Brexit, could rise further.
The group said to help avoid this measures to tackle red tape and improve ports need put in place before Britain exits the EU in March 2019.
Mr Coupe said that the repercussions of supply chain disruption are "not fully recognised" in Westminster.
He also insisted the retail sector will make its voice heard "strongly" if there appears to be a lack of pragmatism during exit negotiations.
Mr Coupe's comments come after the EU's chief Brexit negotiator said there had been no 'decisive progress' in talks with the UK.
Michel Barnier also stressed that negotiators are still "quite far" away from being in a position to begin talks on future trade arrangements.