Morrisons have said it would block any customer from shopping in stores if they refuse to wear a mask without medical exemption.

This comes after chains such as Tesco and Sainsbury's said safety remains their "highest priority" and that customers were given regular reminders to follow the rules.

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."

It comes as vaccines minister Nadhim Zahawi voiced his concerns that members of the public were not complying with measures put in place by supermarkets, amid suggestions the restrictions may need to be toughened.

"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.