Shoppers report delivery problems that have led to empty supermarket shelves in the UK for the second time in six months.
Fresh fruit and vegetables and cold products are especially scarce, customers say.
Many people blame Brexit, but others say it has to do with the rising number of workers self-isolating due to Covid.
Long lines of trucks formed in Calais on Thursday as new import controls on goods from the EU began to gnaw after coming into effect on January 1.
Some people who work in supermarkets or have relatives who do said trucks had not arrived, causing shortages of goods.
Customers in places ranging from South London, Hampshire and Essex to Leicestershire and South Wales said they were unable to buy fresh produce and posted photos of the empty shelves on social media.
But others showed photos of full shelves, suggesting sporadic delivery problems.
Customers who had deliveries also reported that more and more items were not available or replaced.
Sainsbury’s appeared to be the most affected, but people said they had also seen empty shelves at Lidl, Morrisons and the Co-op.
A courier returning from France said it took him 11.5 hours to get from Calais to London because of the truck robberies.
“I should have made a delivery to Heathrow this afternoon,” he tweeted. “That has failed now and it is now tomorrow. It might as well not be urgent (it actually was) #Brexit disaster.”
He said he had driven from Poland to be told his paperwork was wrong, and other drivers who had heard the same risk being forced to drive back to where they came from, leaving lines of trucks in the French port.
Last year, supermarket shortages were attributed partly to post-Brexit truck driver shortages and partly to the “pingdemic”, when workers received warnings on the NHS app asking them to self-isolate for having been in contact with an infected person. .
Ministers appealed to people not to panic buying, although many did, exacerbating the shortages. The first items out of stock were toilet rolls.
A Sainsbury’s spokeswoman said the availability of goods has been strong so any reduction in stock has been isolated for a short time, adding: “All stores continue to receive daily deliveries. We are of course monitoring the situation with absences and we will just keep working.”
The Co-op said it experienced no unusual or significant availability issues.
Helen Dickinson, chief executive of the British Retail Consortium, which represents retailers, said: “Our members continue to work around the clock to ensure shelves are stocked and consumers can buy the products they need.
“Labour shortages, including truck drivers and other critical roles, continue to challenge retailers, and while staff absenteeism due to self-isolation is currently manageable, a further increase in absenteeism rate would become increasingly unsustainable.”
When asked how much of the pressure was due to labor shortages and how much to trucks not arriving because they are delayed at French ports, a consortium spokeswoman said they were unaware, adding: “We actually have no indication of many empty shelves, so we think these are isolated incidents.”