One Government source said: “What we do not want is people to go on to websites and try to order clinical stuff which takes away from the NHS supply.”
Currently, British advice is in line with that of the World Health Organisation and does not recommend mask wearing for the general public.
But a Cabinet minister said that despite the lack of conclusive evidence a consensus was building that they “won’t do any harm”.
“There is a theory that wearing masks might make people less vigilant, but this is about giving people confidence to return to work,” the minister said. “If it makes people feel safer using public transport then it is a good thing, so we are leaning towards it.”
Another Cabinet minister said: “The onus will be on the employers to provide them.”
The move comes after Mr Johnson last week made an apparent off-the-cuff remark that wearing face coverings for returning staff to workplaces would give them “confidence” that they do not risk catching coronavirus.
Speaking at a Downing Street press conference on April 30, he said: “I do think that face coverings will be useful, both for epidemiological reasons, but also for giving people confidence that they can go back to work.”
Mr Johnson’s announcement came a day after Michael Gove, the Cabinet Office minister, said that asking people to wear face masks to protect themselves from coronavirus could make them behave in a “cavalier” manner and risk spreading the virus.
Confirming that the decision was “under review”, he told MPs on April 29: “The scientific evidence so far is that face coverings can have an effect preventing an individual spreading the disease to others if they have it and they are asymptomatic.”
The Scottish government has already recommended that people cover their faces while in some enclosed public spaces such as shops and public transport.
Nicola Sturgeon, the Scottish First Minister, said there could be “some benefit” in wearing a cloth face covering in places where social distancing was difficult but insisted it was “not a substitute” for existing lockdown restrictions.