There are fresh concerns for Britain's supermarkets about how to supply the country's 60 million people without longer opening hours or a relaxation of social distancing rules.

Industry execs speaking on condition of anonymity said they expected a jump in demand once Britons have worked through supplies amassed at the start of the crisis.

In the four weeks before the government restricted movement on March 23rd, UK grocery sales leapt 20% as Britons stockpiled an extra 1 billion pounds worth of food.

Sales growth has slowed over the past fortnight as stores cut their opening hours and limited the number of customers allowed in at any one time.

But executives believe the drop in demand will be short-lived as people shop for the Easter break.

Big supermarkets are budgeting for a 15% to 20% rise in sales volumes during the lockdown, said one source.

That's one reason why Britain's big four - Tesco, Sainsbury's, Asda and Morrisons - are recruiting tens of thousands of staff.

Supermarket online delivery businesses, which accounted for about 8% of the market before the health crisis, are being ramped up to meet some of the extra demand.

But even if delivery capacity doubled, some 85% of the market would still need to be served by stores.

And supermarkets fear that under the current restrictions, they simply cannot physically meet that demand.