Ministers are 'all over the place' on face masks with Boris Johnson and Michael Gove seemingly at odds over whether they should be compulsory.
Scientists have warned that the public will be 'confused' after the Cabinet minister insisted wearing covering indoors should be a matter of 'courtesy'.
Mr Gove's intervention came despite Boris Johnson saying on Friday that the government 'needs to be stricter in insisting people wear face coverings in confined spaces'.
Downing Street sources tried to play down the clash, saying that masks could still be made mandatory in shops in England in the coming weeks. Currently they are only required by law on public transport.
Nicola Sturgeon has already brought the rule in for Scotland, while London mayor Sadiq Khan has been demanding the change.
Royal Society president Dr Venki Ramakrishnan said the 'evidence has shifted' and it was now 'quite strongly in favour of using face coverings in enclosed spaces'.
He told GMB it was 'not consistent' to require masks on public transport but not in shops. 'A virus doens't know. The bahviour of the virus is the same in all of these spaces,' he said.
Boris Johnson appeared in public wearing a face mask for the first time on Friday night, hours after suggesting the Government would become 'stricter in insisting that people wear face coverings in confined places'
Michael Gove sparked confusion yesterday by insisting wearing face covering indoors should be a matter of 'courtesy' rather than required by law
Paul Hunter, a professor of medicine at the University of East Anglia, said the public 'had been confused as hell' by some official advice during the crisis.
'I think we're seeing this again with facemasks,' he told the Times.
A former Cabinet minister said the approach was 'all over the place'. 'If the government wants to be clear about this, they should go one way or the other. Sitting on the fence doesn't really work. People are confused,' they said.
Government sources said ten factory production lines have been acquired to ensure there is enough supply if and when the wider use of coverings is made mandatory.
Half of the businesses, in Wales and Burnley, are already in production with the rest to come on stream next week.
Sources said the move was to make the UK 'resilient' and not reliant on foreign suppliers.
Masks are already compulsory on public transport and the Prime Minister hinted on Friday that the Government is poised to extend the requirement to retail premises to help control the virus spread.
Mr Gove sparked confusion over official policy on the issue yesterday when he said it should not be made mandatory in shops.
Mr Johnson appeared in public wearing a face mask for the first time on Friday night, hours after suggesting the Government would become 'stricter in insisting that people wear face coverings in confined places'.
Masks are already compulsory on public transport and the Prime Minister hinted on Friday that the Government is poised to extend the requirement to retail premises to help control the virus spread
But asked if Downing Street was going to make their use mandatory in shops, Mr Gove told the BBC's Andrew Marr Show yesterday: 'I don't think mandatory, no. But I would encourage people to wear face masks when they're inside in an environment where they're likely to be mixing with others and where the ventilation may not be as good as it might.
'So I think that it is basic good manners, courtesy, consideration to wear a face mask if you are, for example, in a shop.'
London mayor Sadiq Khan, who is campaigning for compulsory mask use, urged ministers to 'get their act together'.
He said: 'Our response is once again behind the rest of the world.'
Tory MP Sir Christopher Chope urged ministers not to make masks compulsory, saying he would stop shopping if required to wear one
A Whitehall source said the Government had now acquired ten production lines, each capable of producing half a million masks per week.
Five are already operating, with the rest expected to complete safety tests within days.
But Tory MP Sir Christopher Chope urged ministers not to make masks compulsory, saying he would stop shopping if required to wear one.
He said ministers should keep things in perspective and be 'trying to build confidence about the nature of the risk involved'.