Morrisons has confirmed customers who refuse to wear a mask without a medical exemption will be told to leave stores from today.

The move comes amid a third national lockdown.

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."

The decision comes after a shopworkers’ union reported being “inundated” with complaints from its members, who say they are “deeply concerned” for their safety as members of the public flout in-store Covid measures.

Usdaw urged supermarkets and food retailers to revert to “stringent” restrictions and said that staff – who are classed as key workers – must be “valued, respected and protected”.

Hillingdon Times: Customers will not be allowed in Morrisons stores without a face maskCustomers will not be allowed in Morrisons stores without a face mask

Chains such as Tesco and Sainsbury’s said safety remains their “highest priority” and that customers were given regular reminders to follow the rules.

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.

Professor Chris Whitty said face masks are extremely important and should not just be worn "as a fashion accessory".

"It's absolutely there to protect other people," England's chief medical officer told a Q&A on BBC Radio 5 Live.

"I really would encourage people - if they are going on buses or on the Tube or to the shops - and do it properly over the nose and mouth and not just as a fashion accessory.

"In terms of outdoor situations, the only risk outdoors is if you're in a crowded environment. Outdoors is much lower risk than indoors."

Earlier today, MPs were advised to wear face masks "wherever possible" in the House of Commons chamber during the lockdown.

The advice came after Boris Johnson has warned that tougher lockdown measures may be needed as he announced that around 2.4 million vaccines for Covid-19 have now been put in people’s arms.

The Prime Minister stressed “now is the moment for maximum vigilance” amid increasing calls for tougher lockdown restrictions as case rates soar in several parts of the country.

During a visit to a vaccine centre in Ashton Gate Stadium, Bristol, the Prime Minister said: “We’re going to keep the rules under constant review.

“Where we have to tighten them, we will.

“We have rules in place already which, if they are properly followed, we believe can make a huge, huge difference.

“It’s now that people need to focus… when they’re out shopping, whether they’re buying cups of coffee in the park or whatever it happens to be, they need to think about spreading the disease.”