Senior minister Michael Gove has said he does not think face coverings should be compulsory in shops in England, saying he trusts people's common sense.
Speaking to the BBC's Andrew Marr, Mr Gove said wearing a mask in a shop was "basic good manners".
On Friday, Boris Johnson said a "stricter" approach was needed so people wear masks in confined spaces.
Senior government sources have said the issue is being kept under review, as Labour called for clarity on the issue.
Currently, face coverings are compulsory on public transport in England, Scotland and Northern Ireland to help stop the spread of coronavirus.
In Scotland, they are also mandatory in shops. Wales recommends masks but they are not compulsory.
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However, there have been calls for the UK government to make its stance on masks clearer, following comments from the prime minister on Friday.
Mr Johnson - who was pictured wearing a mask for the first time during a visit to his constituency - said: "I do think we need to be stricter in insisting people wear face coverings in confined spaces where they are meeting people they don't normally meet.
"We are looking at ways of making sure that people really do have face coverings in shops, for instance, where there is a risk of transmission."
Also on Friday, senior Whitehall sources said the government was considering making face coverings mandatory in shops.
They said while no decision has yet been made, it is an issue that is being kept under review.
The Department of Health and Social Care said on Sunday that 44,819 people have now died in UK hospitals, care homes and the wider community after testing positive for coronavirus, a rise of 21 on the previous day's figures.