The British government has made wearing a face covering compulsory in shops and supermarkets in England from next week.
"The Prime Minister has been clear that people should be wearing face coverings in shops and we will make this mandatory from July 24," a statement said last night from Boris Johnson's Downing Street office.
"There is growing evidence that wearing a face covering in an enclosed space helps protect individuals and those around them from coronavirus," it added.
Britain has been one of the countries worst hit by the coronavirus, with almost 45,000 deaths attributed to it.
Face coverings have been mandatory on public transport in England since 15 June, and Health Secretary Matt Hancock will formally extend that to shops and supermarkets, said Downing Street.
Those who fail to wear a covering face a fine of up to £100 with enforcement to be carried out by the police.
Mr Johnson said last week that tighter rules on wearing face coverings might be needed but senior minister, Cabinet Secretary Michael Gove, said on Sunday that wearing masks should be left instead to people's common sense.
However, during a visit to the London Ambulance Service yesterday, Mr Johnson offered the clearest signal he was going down the route of compulsion, saying the Government was looking at the "tools of enforcement".
The move will bring England into line with Scotland, where face coverings are already mandatory in shops.
Enforcement of the regulations will be the responsibility of the police.
While shop workers will be asked to encourage compliance, retailers and businesses will not be expected to enforce them.
Report warns of 'second wave'
Meanwhile, scientists advising the British government have warned that a second wave of coronavirus infections this winter could be more serious than the first, with 120,000 UK hospital deaths in a "reasonable worst-case scenario".
A new report from the Academy of Medical Sciences, commissioned by the government's chief scientific adviser Patrick Vallance, says action must be taken now to mitigate the potential for a second peak of Covid-19.
It argues that hospitals could potentially see 120,000 Covid-19 deaths in between September and next June at the same time as battling a surge in demand due to usual winter pressures, including flu.
The report, from 37 scientists and academics, acknowledges there is a high degree of uncertainty about how the Covid-19 epidemic will evolve in the UK over the coming months, but sets out a "reasonable worst-case scenario" that would see the R rate rise to 1.7 from September.
The R refers to the number of people an infected person can be expected to pass the virus on to.
The academic modelling suggests there could be a peak in hospital admissions and deaths in January and February 2021, similar to or worse than the first wave in spring 2020. It does not include deaths in the community or care homes.
The figures do not take account of government intervention to reduce the transmission rate, or the use of the drug dexamethasone in intensive care units, which has been shown to cut deaths.
Professor Stephen Holgate, a Medical Research Council clinical professor of immunopharmacology who led the study, said: "This is not a prediction, but it is a possibility.
"The modelling suggests that deaths could be higher with a new wave of Covid-19 this winter, but the risk of this happening could be reduced if we take action immediately.
"With relatively low numbers of Covid-19 cases at the moment, this is a critical window of opportunity to help us prepare for the worst that winter can throw at us."