As France entered a new national lockdown on Friday, President Emmanuel Macron also made face masks compulsory for primary school children aged six and over.
Previously, only children aged 11 or over had been instructed to wear masks in French schools, while other European countries have also adopted different approaches.
Spain and Italy have made masks compulsory since September, but in England only children aged 11 or over can be asked to wear them in schools, and even then the UK government says they should not wear them in classes.
In Germany and the Netherlands they are not obligatory.
The conflicting measures put in place by European nations have left parents across the continent asking whether primary school children should be wearing masks.
European countries have issued different rules regarding the wearing of face masks by children, prompting the World Health Organization to clarify their recommendations for different age groups./AP
The issue was addressed at a media briefing hosted by the World Health Organization. Maria van Kerkhove, head of the WHO's emerging diseases and zoonosis unit, said: "We know that children can be infected, most of them have a very mild disease and many of them are asymptomatic, but they can be infected and they can transmit.
"We use that information to better understand what is happening within children as schools open up."
She said there had not been a change to the WHO guidance issued in August on the use of masks by children.
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She summarized the key points: "For children what we recommend is that under six years old, we don't recommend the use of masks, for many reasons - because of the way children are developing, the adherence to wearing them, many reasons.
"Between 6 to 11, we recommend taking a risk-based approach depending on where the children are, the types of activities they are doing, if they are being monitored, because if they are wearing a mask there are some risks associated, they need to be worn safely.
"Twelve years and older we recommend the same recommendations as adults."
The WHO guidance for these secondary school pupils is to wear a face mask if social distancing is not possible and if there is widespread transmission in the area.