Online supermarket Ocado has advised customers to place orders further in advance because of "exceptionally high demand", indicating a possible reaction from shoppers to the spreading coronavirus outbreak.
Britain announced a jump in coronavirus cases on Sunday, with 13 new infections taking the total to 36 and Prime Minister Boris Johnson warning that the number is likely to rise.
Ocado e-mailed some customers on Friday to warn of high demand for its delivery service.
"More people than usual seem to be placing particularly large orders. As a result, delivery slots are selling out quicker than expected," it said.
The company advised customers to place orders further in advance than they might normally; ideally, two or three days before.
It also asked customers to book weekday delivery (Monday to Thursday) rather than weekends if they are able to be flexible.
Ocado declined to comment further.
Britain's traditional big four supermarkets - industry leader Tesco, Sainsbury's, Asda and Morrisons - did not have any immediate comment when asked if they had seen an upturn in demand for their online services as Britons start to avoid social contact.
Separately on Monday, Bernstein food retail analyst Bruno Monteyne cautioned that in a pandemic scenario parents and carers of the sick will be unable to work, leading to a broader impact on supply chains than only those who become ill.
"With tight supply chains, if a major outbreak happens, that will quickly lead to panic buying, empty shelves and food riots," he said in a note published on Monday.
Monteyne said the industry will be drawing up plans with suppliers to rationalise product ranges and transition to a "feed-the-nation" status when necessary.
He forecast that sales would be resilient but profit would take a hit because retailers will be reluctant to pass on to shoppers the temporary operational costs of dealing with the disruption.
