Tesco has announced six rules that shoppers must obey, or they will be asked to leave.
The toughening of measures at Britain's biggest supermarket follow the third lockdown for England, which critics say does not go far enough.
After Morrison's took a hardline stance by banning customers who refused to wear masks, Tesco, Sainsbury's, Asda, Aldi, M&S and Waitrose followed suit and strengthened their rules, Birmingham Live reports.
The CEO of Tesco UK, Jason Tarry, said: "Since the start of the pandemic, we’ve focused on ensuring everyone can get the food they need in a safe environment.
"Our safety measures are there to protect you and our colleagues, as we all follow the latest government guidance.
"Now that strict national lockdown measures are in place again, we wanted to share an update on some of the ways we’re supporting you to shop safely."
It's a legal requirement to wear a face covering in stores, and police are stepping up patrols across the UK to enforce this law.
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"To protect our colleagues and customers, we won’t let anyone into our stores who isn’t wearing a face covering, unless they’re exempt in line with government guidance. Please also make sure that you wear your face covering correctly – covering your mouth and your nose."
Bosses have issued the following rules:
Shop alone
"Please shop alone unless you’re a carer or with children. We also encourage you to shop only when you need to, in line with government guidance to stay at home."
One-in, one-out
"We continue to limit the number of people in our stores and we have a ‘one-in, one-out’ system in place to ensure social distancing."
Wait for the green light
"We have introduced a traffic light system at more than 1,300 of our store entrances. The system monitors numbers and will light up green when you can safely enter. If the light is red, then the limit has been reached and our colleagues will ask you to join a queue outside the store."
Sanitise your hands, basket and trolley
"We have cleaning stations in our stores so that you can sanitise your trolley or basket, and you’ll find plenty of hand sanitiser around the store to use while you shop."
Online shopping and deliveries
"If you’re shopping online, our colleagues will maintain a safe distance when they deliver your shopping, and they will regularly sanitise their hands and equipment.
"Please help us to free up online slots for those who need them most by shopping in-store if you’re able to do so safely."
