The use of face coverings in corridors and communal areas of secondary schools is set to be introduced in Scotland.
The government is in the “final stages” of consultations with teachers and councils about having pupils wear face coverings while moving between classes.
First Minister Nicola Sturgeon said she was acting in response to new guidance from the World Health Organization.
However, there are not currently any plans to have pupils wear masks while in the classroom.
The use of face coverings in schools is currently voluntary, although some schools have started advising staff and pupils to wear them to help combat Covid-19.
Young people returned to Scotland’s schools earlier in August with no requirements for physical distancing between younger pupils, and no rules around face coverings.
However, over the weekend the World Health Organization (WHO) issued fresh guidance saying children over the age of 12 should wear masks.
At her daily coronavirus briefing, Ms Sturgeon said Education Secretary John Swinney was “in the final stage of consulting teachers and local authorities for the use of face coverings in secondary schools when moving around corridors and communal areas”.
She said there was more mixing between different groups of children in these areas, and that there was less scope for effective ventilation.
Pupils are also thought to be more likely to raise their voices in crowded areas, increasing the risk of aerosol transmission of the virus.
Ms Sturgeon said the government’s scientific advisers were also considering whether face coverings should be made mandatory on school transport.
However, she said they were “not currently consulting on any proposal” to have pupils wear masks in class, saying: “There is greater scope for physical distancing in classrooms and [face coverings] are more likely to interfere with teaching and learning.”
She added: “The best way to ensure schools can stay open safely is for all of us to play our part in keeping transmission rates in the community as low as possible.”
Some schools in Edinburgh, Inverness and Grantown on Spey have written to parents recommending pupils wear masks due to concerns about overcrowding as they move between lessons.
The first minister said the Scotland-wide move could be confirmed “over the next couple of days”, and would constitute a change to guidance.
She said: “We are not talking about a mandatory system in the sense of there being penalties and enforcement in schools. I get the sense that schools – while I accept there will be a mixture of opinion around it – are themselves looking to follow this kind of approach.
“We will set out the detail when we get to the point of finalising the recommendation.”
Health authorities are working to tackle a number of coronavirus “clusters” in Scotland, including one centred on the Kingspark School in Dundee.
A total of 17 members of staff have tested positive, as well as two pupils, and all households connected to the school have been told to go into self-isolation for two weeks.
A growing number of school pupils across Scotland have tested positive for Covid-19, but the government believes the infection has been transmitted in other settings such as house parties.
Ms Sturgeon said “most” transmission of the virus was not happening in schools, saying that “the risk is greater of community transmission getting into schools”.