Pupils and teachers wearing masks is an option that should be kept under review, a heads’ union has said, despite the education secretary insisting that the measure is not needed as schools in England prepare to reopen.

The call comes after the Scottish government issued ‘obligatory’ guidance on wearing face coverings in secondary schools in light of the latest guidance from the World Health Organisation (WHO) that students aged 12 and over should wear a mask.

The Association of School and College Leaders said that, as evidence continued to emerge, Westminster should review its guidance.

ASCL general secretary Geoff Barton told The Daily Telegraph: “We would expect the government in Westminster to review its guidance on the use of face coverings in schools - which currently says they are not required - in light of the WHO guidance and the consultation taking place in Scotland.

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“The evidence is clearly evolving on this issue and it is important that it is kept under review and that clear direction is provided to schools.”

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But Professor Russell Viner, a member of the government’s Scientific Advisory Group for Emergencies (Sage), said there was concern about younger children wearing face coverings.

He told BBC Two’s Newsnight: “The evidence on masks is very unclear. And, actually, I think that is, in one sense, potentially going beyond the evidence we have.

“There are lots of concerns about mask wearing for children, particularly younger children. Because they touch their face, they are constantly worried about the mask. It actually could, potentially,spread the virus more.

“I think for young children it [would be] clear it is not a good idea. For teenagers, again, I think, we don’t have the evidence this is useful.”

Yesterday, a Number 10 spokesman said there were “no plans” to review the guidance on face coverings in schools.

He added: “We are conscious of the fact that it would obstruct communication between teachers and pupils.”

England’s deputy chief medical officer, Jenny Harries, has said the evidence on whether children over 12 should wear masks in schools was “not strong”, while education secretary Gavin Williamson said measures being adopted by schools to limit the spread of the coronavirus meant masks were not required.

The World Health Organisation’s advice suggests adults and children aged 12 and over should wear a mask, particularly when they cannot guarantee at least a one-metre distance from others and there is widespread transmission in the area.

The WHO and UN children’s agency Unicef suggested that face shields may be an alternative in situations such as speech classes where the teacher and pupils need to see each other’s mouths.

Shadow education secretary Kate Green has already said the issue should be kept under review.

Secondary students in Scotland will have to wear face coverings in school corridors and communal areas, and on buses, from Monday.

Meanwhile, a study suggests that wearing face masks may have a negative effect on attitudes towards social distancing, leading people to feel comfortable sitting or standing closer to others

The research, by a team of behavioural scientists at Warwick Business School, also indicates that people would keep a smaller distance from others wearing masks.

The scientists say their findings could make it difficult to re-establish social-distancing measures if they are needed to help to control the virus in the event of a second wave of cases.