A 'no-deal' Brexit would lead to higher prices, empty shelves and pose a threat to the UK's food security, retailers have warned.
UK retailers' industry group the British Retail Consortium has written to MPs with the warning, saying that the food retail sector's complex just-in-time supply chain will be significantly disrupted in the event of no deal.
The letter was co-signed by UK retail giants, including the chief executives of Marks & Spencer, Waitrose, Sainsbury, Asda and Morrisons.
The bosses of Co-op, Costcutter, Lidl, KFC and McDonalds also signed the letter.
The letter responded directly to the government's own projection that freight through Calais may fall 87% from current levels, threatening the availability and shelf life of many products.
It said: "Even if the UK government does not undertake checks on products at the border, there will still be major disruption at Calais as the French government has said it will enforce sanitary and customs checks on exports from the EU, which will lead to long delays.
"For consumers, this will reduce the availability and shelf life of many products in our stores."
The warning comes days after Sky News learned that Britain has begun stockpiling food, fuel, spare parts and ammunition at military bases in Gibraltar, Cyprus and the Falklands in case of a no-deal Brexit.
The BRC letter expresses concerns about tariffs, with only 10% of all food imports currently subject to World Trade Organisation (WTO) rules.
The retailers are warning that if the UK reverts to WTO rules, following departure from the European Union in March, the tariffs would "greatly increase import costs that would in turn put upward pressure on food prices".
The UK depends heavily on EU food imports, with nearly one-third of the food in the UK coming from the bloc alone.
"In March, the situation becomes more acute as UK produce is out of season," the letter says.
The letter points out that at that time of year, 90% of lettuces, 80% of tomatoes and 70% of soft fruit sold in the UK is grown in the EU.
The BRC has previously warned of the risks associated with leaving the European Union without a deal, including the risk of higher food prices.