Average spend increased by 16% month-on-month to 22.13 pounds, the market research firm said, as shoppers spent more on groceries and less on other categories like clothes.

Kantar said supermarkets, which have had to introduce rationing to help cope with demand, took 51% of all retail sales, an increase of 7 percentage points on the same week in mid-February.

High streets emptied over the weekend as shoppers heeded government advice to avoid unnecessary trips, with footfall down 41% according to Springboard.

Major retailers such as Primark, Debenhams and John Lewis department stores have closed stores, while restaurant chains McDonald's, Nando's and Pret a Manger have also shut up shop. Food-to-go chain Greggs will close on Tuesday.

Kantar said only a minority of shoppers were engaging in stockpiling, with 6% of liquid soap buyers taking home extraordinary quantities, and only 3% of dry pasta shoppers, according to its analysis of 100,000 shoppers. 

Kantar's head of retail and consumer insight, Fraser McKevitt, said images were circulating online of people bulk buying products like toilet rolls and pasta, but Kantar's data gave a different diagnosis of what was happening.  

"Ultimately we need to look at the empirical evidence and it tells us that temporary shortages are being caused by people adding just a few extra items and shopping more often ? behaviour that consumers wouldn't necessarily think of as stockpiling," he said.  

"People will also be eating in more as a result of social distancing and increased working from home. 

"Consumers spend more than 4 billion pounds each month on food and drink out of the home, a significant proportion of which will now be channelled through the supermarkets."

(Reporting by Paul Sandle; editing by Kate Holton and Angus MacSwan)