People could be fined for not wearing face coverings correctly under sweeping new regulations on mask usage in shops, takeaway outlets and transport hubs.
From Friday, it will be compulsory to sport a face covering in all shops and supermarkets in England, as well as indoor shopping centres, post offices and banks.
The public will also be required to wear a mask while buying takeaway food and drink, such as in a cafe, but restaurants and sit-down eateries are exempt.
Police have the power to fine people up to £100 for failing to obey the new regulations, which were published only hours before the changes were due to come into effect.
The regulations state that a face covering “covers a person’s nose and mouth” – meaning those who wear the mask without covering their nose could be breaching rules.
Anyone flouting the rules can be slapped with a £100 penalty, which reduced to £50 if paid within 14 days.
Police have legal powers to enforce the rules but they are expected to only use them as a last resort.
Downing Street played down the prospect of fines, saying people would be advised on how to wear a mask correctly.
Asked whether people would be fined for incorrect usage, the Prime Minister’s official spokesman said: “I think what would happen at that point is people would be given the advice as to how properly to wear it to ensure it’s effective.
“That would be the sensible approach.”
The PM’s spokesman said No10 did not expect members of the public to report those who were not wearing masks in shops from Friday due to voluntary take-up of the policy.
He said: “You’ve seen over the course of recent months the British public have voluntarily chosen to follow the guidance because they want to help slow the spread of the virus and I’m sure that will be the case with face coverings as well.”
Some people are exempt from the new rules, such as anyone with a disability that means they cannot put on a face covering or someone accompanying another person who relies on lip reading.
Children under 11-years-old, shop staff, and police and emergency service workers are also exempt.
The new guidance was released at the eleventh hour, following confusion from senior ministers about where the new regulations apply.
Northern Ireland Secretary Brandon Lewis confirmed on Thursday that masks would be mandatory in takeaways – despite his Cabinet colleague Alok Sharma saying the opposite the week before.
And Mr Sharma, the Business Secretary, had himself contradicted Health Secretary Matt Hancock, who said they would be compulsory in places like sandwich shops and cafes.