Making face coverings mandatory in shops in England is being considered by the government to slow the spread of coronavirus, senior sources have said.
No decisions have yet been made, but the issue is being kept under review.
Speaking in a Facebook Q&A video, Boris Johnson hinted at the change saying: "We are looking at ways of making sure that people really do have face coverings in shops."
Face coverings have been compulsory in shops in Scotland since 10 July.
The UK government was initially hesitant about advising people to wear face coverings, arguing that evidence that they reduce transmission was "weak".
However, rules compelling people to wear face masks on public transport in England were introduced on 15 June.
And speaking on Friday Mr Johnson said "the balance of scientific opinion seems to have shifted more in favour of them than it was, and we're very keen to follow that".
"I don't think we are going to get to a world where we say everyone has to wear face coverings the whole time everywhere," he said, but added "We need to be stricter in insisting that people wear face coverings in confined spaces where they are meeting people they don't usually meet".
"The future for the country has got to be a world where we are managing the virus so effectively with local lockdowns, test and trace that we don't need ultimately to have some of these social distancing measures."
The rules on face covering vary across the nations. In Scotland face coverings are mandatory in shops and on public transport.
People in Wales are being asked to wear non-medical face coverings where social distancing is not possible - including on public transport - but the government in Cardiff stopped short of making their use mandatory.
While in Northern Ireland, plans to make wearing face coverings on public transport compulsory have been put on hold, pending legal clarification.
The World Health Organisation says non-medical face coverings should be worn where social distancing is not possible.