Morrisons has become the first UK supermarket to ban shoppers who refuse to wear a mask unless they are medically exempt, and Sainsbury's will post trained security guards at shop entrances to “challenge” any customers not wearing a mask or shopping in groups.
Morrisons Chief executive David Potts said: “Those who are offered a face covering and decline to wear one won’t be allowed to shop at Morrisons unless they are medically exempt.
"Our store colleagues are working hard to feed you and your family, please be kind.”
Earlier on Monday, the shopworkers' union Usdaw said they had been “inundated” with complaints from its members, who say they are “deeply concerned” for their safety as customers flout in-store Covid measures.
Sainsbury's Chief executive Simon Roberts said: "The vast majority of customers are shopping safely, but I have also seen some customers trying to shop without a mask and shopping in larger family groups.
"Please help us to keep all our colleagues and customers safe by always wearing a mask and by shopping alone. Everyone’s care and consideration matters now more than ever.”
Tesco said it was still enforcing social distancing practices in store but was not looking yet at reintroducing measures such as one-way aisles.
The supermarket chain said it would also significantly reduced the number of customers allowed into stores at any one time.Data from Public Health England last week found 11 outbreaks of the disease had come from food outlets.
Chains such as Tesco and Sainsbury’s said safety remains their “highest priority” and that customers were given regular reminders to follow the rules.
Vaccines minister Nadhim Zahawi has also voiced his concerns that the public are not complying with the regulations.
“I am worried about supermarkets and people actually wearing masks and following the one-way system and making sure when it’s at capacity they wait outside the supermarket,” he said.
Usdaw general secretary Paddy Lillis said: “Retail staff are working with the public every day and not only suffer increased abuse, but are deeply worried about catching Covid-19.
“Where safety measures are agreed, retailers need to make sure that they are being followed consistently, in every store.
“Supermarket workers and delivery drivers have worked throughout the pandemic to keep the country supplied with essentials.
“These key workers must be valued, respected and protected.”