Wearing a mask will be a must in crowded areas of Paris from Monday amid an increase in coronavirus infections in and around the French capital.
Police said the order would apply to people 11 and older in “some very crowded areas”.
They say the virus has been circulating more widely in the area since mid-July. Masks have been required in enclosed public spaces.
Experts have warned that France could lose control of Covid-19 “at any time”.
Some cities, such as Nice and Lille, have come up with their own additional orders forcing the mask on in some outdoor areas.
The Paris authorities have yet to detail which areas will be affected by the new order, which will take effect at 08:00 (06:00 GMT) on Monday.
Areas where masking is required will be assessed on a regular basis, they said.
In a statement on Saturday, the authorities said the coronavirus-positive test rate was 2.4 percent larger in the greater Paris region, compared with the national average of 1.6 percent.
They added that 400 people tested positive for coronavirus every day in the area, with people between the ages of 20 and 30 being particularly affected.
Officials earlier this week said they had called for new measures on the masks in the French capital.
“We’ll ask that [mask-wearing] Anne Souyris, deputy mayor in charge of health, said it became a must in crowded outdoor areas and where it was difficult to respect the distance between people.
The new order comes after the government’s scientific advisers warned on Tuesday that France could lose control of the virus “any time”.
France reported 2,288 new coronavirus infections in its daily data on Friday, marking a new high after lockout.
In total, the country has recorded more than 235,000 coronavirus infections and more than 30,000 deaths, according to data compiled by Johns Hopkins University.