Cabinet minister Michael Gove does not believe people in England should be forced to wear masks in shops, explaining he trusts their common sense.
Face coverings are currently compulsory on public transport in England, Scotland and Northern Ireland, while Scotland has also enforced it in shops.
During an appearance on the BBC's Andrew Marr programme, Mr Gove said it was "basic good manners" to wear a mask.
He said: "I don't think mandatory, no, but I would encourage people to wear face masks when they are inside, in an environment where they are likely to be mixing with others and where the ventilation may not be as good as it might.
"I think that it is basic good manners, courtesy and consideration, to wear a face mask if you are, for example, in a shop."
On Friday, Prime Minister Boris Johnson said a "stricter" approach was needed for more confined spaces. But the government says the issue is being kept under review. This prompted calls from opposition parties for the government to provide clarity on its stance.
During a visit to his constituency, Mr Johnson, who was pictured wearing a mask, 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."
Labour said it supports a move to compulsory mask-wearing in shops, explaining it may actually help to encourage greater spending.
Shadow Cabinet Office minister, Rachel Reeves, said it would inspire greater confidence and might encourage more people to go out and spend money".
"I think people are increasingly wearing them but I think some greater clarity from government about that, I think, would be helpful," she said.
"People want to do the right thing but they want to know what the right thing is. We already have it on public transport."
