Video report by ITV News Consumer Correspondent Chris Choi
People will need to wear a face covering in sandwich shops in England under new regulations due to come into force on Friday.
It will also be mandatory to wear a face covering in shopping centres, banks, takeaway outlets and supermarkets under the new regulations.
Health secretary Matt Hancock urged the public to "play their part in fighting this virus by following this new guidance" as the government sought to clarify confusion over face coverings by publishing new regulations on Thursday - less than 24 hours before they come into effect.
The Department of Health and Social Care confirmed face coverings will be needed in shops such as Pret A Manger if people intend to take their food and coffee away.
If they sit down to eat or drink, customers will be able to remove their face covering in that area and it is likely takeaway outlets will fall under the same criteria.
Government minister Brandon Lewis told ITV News: "If you're going in to buy your sandwich or your coffee, and leaving again you're treating it as a retail environment and you should be wearing a mask.
He added: "But if you're staying there to eat, and drink, then practicality means, yes you can take your mask off, because then you're there as a hospitality venue rather than a retail venue, that's the simplest way to think of it."
Mr Lewis also clarified the regulations around face coverings generally: "When you go into a supermarket or retail environment you should be wearing a mask."
The government has been accused of creating confusion over whether face coverings must be worn in sandwich shops and takeaways, after Rishi Sunak was pictured wearing a face covering in sandwich chain Pret A Manger, but Michael Gove was not.
But will shops be made to enforce the guidance?
While shops, supermarkets, indoor shopping centres and transport hubs, banks, building societies and post offices all fall under the new regulations - wearing a face covering in places such as restaurants and pubs, hairdressers, gyms, leisure centres, cinemas, concert halls and theatres will not be mandatory.
Prime minister Boris Johnson said it was "the right thing to do" to make masks mandatory in shops at this stage as the science has become "clearer" on their usefulness.
"The purpose of the masks is to stop any of us transmitting the virus to anybody else.
"It's a mutually beneficial thing and it's the right thing to do in shops, in confined spaces where you're in company with people you don't normally meet, and also, of course on public transport," he said."There's been dispute, I think, amongst the scientists over the course of the pandemic about the utility of the mask, but the advice is getting clearer and clearer, that they can be of benefit.
"So we're saying 'wear them in shops, wear them on public transport'."
Kevin Duffy, Director of Centre:MK shopping centre in Milton Keynes, told ITV News he doesn’t think it’s likely that many people will turn up to shops refusing to wear face masks - and that he expects “most people will play their part”.
The same exemptions as for public transport will apply to wearing a face covering in shops, with children under 11 and people with breathing problems not required to wear one.
Anyone who cannot put on, wear or remove a face covering because of a physical or mental illness or impairment or disability is also exempt.
The government has been urged to do more to protect people exempt from wearing a face covering after a charity highlighted “horrific” cases of disabled people being abused.
Fazilet Hadi, a policy manager at Disability Rights UK, said she has already heard several stories of people being confronted on public transport – where masks have been mandatory since June – despite having legitimate reasons for not wearing one.
How to wear face masks:
A government spokesperson said: "The guidance is absolutely clear that you do not need to wear a face covering if you have a legitimate reason not to, including because of a physical or mental illness or impairment, or disability.
“We expect people to be sensitive to the fact that some groups of people are not able to wear a face covering, and will continue to communicate this message to the general public.”
The public are advised to wash their hands before putting a covering or mask on or taking it off, and to avoid touching their eyes, nose, or mouth while wearing one.
Face coverings should be stored in a plastic bag until they can be washed or disposed of, the Department of Health said.
The government said the responsibility for wearing a face covering “sits with individuals”, adding: “Businesses are encouraged to take reasonable steps to encourage customers to follow the law, including through signs and providing other information in store.”
ITV News Correspondent Paul Davies on why shops are relying on polite notices to help encourage customers to wear face mask
Mr Hancock announced on July 14 that wearing a face covering in shops and supermarkets will be compulsory from Friday July 24 - with anyone failing to comply facing a fine of up to £100.
The opposition has accused ministers of “making things up as they go along” over takeaways and sandwich shops.
The latest changes will bring bring England into line with Scotland, where face coverings are already mandatory in shops.
Liberal Democrat health spokesperson Munira Wilson said that with just a day to go to the new guidance being enforced, the government was in a mess.
“People need a government that can offer genuine reassurances and steer the country to safety," she said.
“After all, clear communication is critical in a public health crisis. Instead, this confusion on guidance shows Ministers simply could not organise a bun fight in a bakery.
“All this stinks of ministers making it up as they go along instead of listening to the experts.
“The government must urgently provide the clarity businesses need to operate and people need to feel safe.”
Former head of the civil service Lord O’Donnell told peers on Wednesday the government needed to improve its communications.
Giving evidence to the Lords Public Services Committee, he said: “If anyone knows what the clear message on masks is, please tell me.”