Face masks should be made mandatory in shops “immediately” as a delay will “risk lives”, the Mayor of London has warned.
Boris Johnson said that people in England will have to wear masks in shops as “extra insurance” against the virus.
But the new rule will not come into force until 24 July – more than a week after the announcement.
Mr Khan said the Government has been too slow to act and “can’t afford to wait another day”.
The Mayor has lobbied ministers to extend the rules on face masks, which have be mandatory on public transport in England for a month.
He wrote to the Prime Minister last Friday (10 July) – as masks became mandatory in shops in Scotland – urging England to follow Nicola Sturgeon’s lead north of the border.
Mr Khan said there is “clear overwhelming expert scientific advice” that face coverings slow the spread of Covid-19.
While masks don’t protect the wearer from catching the virus, emerging evidence suggests they can stop people spreading it to others.
Anyone with Covid-19 symptoms – high temperature, a new or continuous cough, and loss of smell or taste – should isolate at home for seven days.
But masks are a useful defence for those who have the virus but are not showing symptoms.
Up to 40% of coronavirus cases could be asymptomatic, according to research by Imperial College London and the University of Padova, Italy.
The British Medical Association called on the Government last month to make masks mandatory in shops.
And the Royal Society – Britain’s leading science body – said last week that no one should leave the house without a face covering.
Now ministers have taken action – and under the new rules, anyone who isn’t wearing a mask could face a £100 fine unless they have a valid medical reason.
Shop staff will not have to wear face coverings, according to Environment Secretary George Eustice.
It comes after the two metre social distancing rule was relaxed two weeks ago (Saturday July 4) as pubs and restaurants in England reopened for the first time.
People from different households should stay two metres apart where possible, but can now be as close as one metre if necessary.
They should take precautions like sitting side-by-side rather than opposite each other, keeping interactions brief, and washing hands regularly.
The Mayor said he was pleased the Government has heeded expert advice on face coverings in shops – but wished there had been action sooner.
“It’s a disgrace that there’s been days of mixed messages and confused communications from ministers,” Mr Khan said.
“Time and time again this government have been slow to act and unclear in their advice and as a result the public’s health that’s been placed at risk as a result.
“We can’t afford to wait another day and the Government should bring this policy in immediately – further delay risks lives.”