Up until now face masks had been mandatory for pupils aged over 11, so those attending colleges (secondary schools) and lycées (high schools).
But the government has extended the rule to all pupils in primary schools. Children attending pre-school (écoles maternelles) will not have to wear the mask.
The measure was announced by PM Jean Castex a day after President Emmanuel Macron declared a new lockdown in France starting from Friday.
Castex told lawmakers in parliament that new efforts were needed “to protect all our children, teachers and parents.”
In contrast to the lockdown in spring the president and the government has decided to keep schools open, albeit with tighter sanitary rules in place.
“We have learnt the lesson from the first wave,” said the Prime Minister.
“Last spring massively increased the risk of school drop-outs, particularly among those in deprived areas,” he said.
“From Monday, when children return to school, the sanitary protocol will be made stricter. The requirement to wear a face mask will be extended to primary school children over the age of six.”
On Thursday France's Minister of Education added more details on the stricter protocol for schools.
He confirmed measures to limit the movement of pupils around the school would be taken and staggered lunch times and break times would be introduced so pupils do not all sit down together.
The disinfection and cleaning of schools would be more rigorous.
Blanquer added that 27 schools out of 61,500 in France were currently closed due to Covid-19 outbreaks, which the minister said confirmed that schools were not places where the virus spread easily.
“A school is a secure place,” he said.