Asda and Tesco are the latest supermarkets to ban people without masks from their stores - which means all four major supermarkets have now imposed the strict measures.
On Monday, Morrisons said it will enforce mask-wearing unless customers are medically exempt, while Sainsbury’s is to place security staff at entrances to “challenge” shoppers who are not wearing masks or who enter stores in groups.
As of Tuesday, what are the rules and conditions for masks at the UKs supermarkets?
Morrisons was the first supermarket to announce the ban.
Customers who are not medically exempt will be offered a face mask and if they refuse to wear them, entry into the store will be denied, unless exempt from wearing one.
Morrisons Chief executive David Potts said: "Our store colleagues are working hard to feed you and your family, please be kind.”
Asda will also offer a face mask to those not wearing one.
A spokesperson said: “If a customer has forgotten their face covering, we will continue to offer them one free of charge – but should a customer refuse to wear a covering without a valid medical reason and be in any way challenging to our colleagues about doing so – our security colleagues will refuse their entry.”
Sainsbury'sSainsbury’s has said it will post trained security guards at shop entrances to “challenge” any customers not wearing a mask or shopping in groups.
Chief executive Simon Roberts said: “I’ve spent a lot of time in our stores reviewing the latest situation over the last few days and on behalf of all my colleagues, I am asking our customers to help us keep everyone safe.
“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.”
On Tuesday, Tesco also said it would not let customers in unless they're wearing a mask unless they were exempt in line with Government guidelines. A spokesperson added that shoppers should be “kind, patient and respectful” towards staff.
A spokesman said: “We are also asking our customers to shop alone, unless they’re a carer or with children.
“To support our colleagues, we will have additional security in stores to help manage this.”
Waitrose also announced new strict rules on Tuesday. It said in a statement: "Marshals will be positioned at the entrances of all supermarkets.
"They will have disposable masks available for customers who do not have their own and will deny admission to anyone refusing to comply."
They marshalls will also ensure that only one member of each household is permitted to shop.
The Co-op did not confirm whether it would ban customers without masks but said it will increase its in-store messaging.
Asked whether Co-op Food stores will take similar steps, chief executive Jo Whitfield said all customers “must take responsibility for wearing a face mask”.
She said: “We’ve increased our in-store messaging to remind customers and Government guidance does state that the police can take measures if members of the public don’t comply with this law.”
Lidl also did not confirm whether it would enforce a total mask ban. It said it continually evaluates and develops its Covid-19 measures. "We will be developing measures across the vast majority of our stores," a spokesperson said.
"This includes positioning security guards at store entrances to regulate customer numbers and to remind those not wearing a face covering of the government guidelines and their own responsibility to keep themselves and others safe."