France will impose COVID-19 tests taken within 24 hours of departure for unvaccinated travellers from the United Kingdom, Spain, Portugal, Cyprus, Greece and the Netherlands, the Prime Minister's office said on Saturday.
So far tests had to be performed within 48 hours of departure for UK travellers, and 72 hours for the other countries targetted by the new rule.
The measure will enter into force from midnight on Sunday.
It comes amid concerns over the fast-spreading Delta variant, which is fueling a wave of new infections across many European countries.
The UK recorded more than 51,000 new infections on Friday — the highest daily tally since January 15.
According to health authorities, 99% of new cases are from the Delta variant, which was first detected in India.
In France, 10,908 new cases were confirmed in the 24 hours to Friday afternoon, as well as 22 deaths.
On Friday, the British government announced that fully vaccinated people returning to the UK from France will still need to quarantine for 10 days.
France also announced on Saturday that Tunisia, Mozambique, Cuba and Indonesia had joined the country's "red-list" with high virus risk.
Paris will allow international travellers who have had AstraZeneca's vaccine made by India's Serum Institute into the country starting Sunday, the Prime Minister's office said.
The move came after global outrage over the fact that the European Union's COVID-19 certificate only recognises AstraZeneca shots manufactured in Europe. Several countries in the bloc already accept the Indian version.
France still does not recognise vaccinations by Chinese or Russian jabs, with only those authorised by the European Medicines Agency accepted.