France will extend a 6pm-to-6am curfew to the whole of the country, Prime Minister Jean Castex has announced.
The curfew will come into force on Saturday and last for "at least" 15 days, he added.
A nighttime curfew running from 8pm to 6am was first introduced on December 15, following a nationwide lockdown.
Around two dozen of France's 95 départements - mainly in the east - have since been given stricter curfews starting at 6pm.
This 12-hour curfew has now been extended to the whole country.
Castex said on Thursday that "while the resumption of the epidemic was concentrated at the end of December in certain departments, viral circulation now concerns the entire country."
He added that the average incidence rate across the country is now above 50 cases per 100,000 inhabitants.
Any public place receiving people will thus need to be closed at 6pm at the latest, Castex said, and people outside their home past that time will need to justify their movement.
The measure is "graduated and proportionate", Castex argued, as the current epidemiological situation "does not justify a new lockdown". He stressed however that a third national lockdown could be imposed if a "strong epidemic degradation" is observed.
"Our situation is worrying even if it has generally stabilised," Castex continued, describing it also as "under control compared to what we see in our neighbours," but "fragile because the virus is still circulating actively on our territory".
The country currently registers an average of 16,000 new infections every day. The pressure on hospitals "remains stable but is at a high level", Castex emphasised.
There were 24,769 people hospitalised for COVID-19 across France on Wednesday, including 2,711 in intensive care.
To prevent the spread of two variants identified in the UK and South Africa, which have been found to be more transmissible, the government also decided to "strongly tighten the conditions of entry on the national territory".
Anyone from outside the European Union will need to show a negative test before travelling and will have to submit to a seven-day quarantine, at the end of which they will have to do a second test.
For travellers from other EU member states, Castex said the government is working on a coordinated framework to be discussed at the European Council summit on January 21.
Additionally, the government said one million children and teachers will be tested monthly going forward to prevent the spread of the variants as children have been found to be more vulnerable to them.