The French government's order to make mask-wearing mandatory came into effect on Monday amid signs of worrying acceleration of the virus circulation and growing number of clusters.

Wearing face mask is now compulsory for all people older than 10 years in restaurants and hotels, shops, covered markets, museums, cinemas, concert halls, places of worship, airports and stations, libraries, vacation centers, administrations and banks, Xinhua news agency reported.

Any person who refuses to apply to the decree to wear the mask in enclosed public spaces will pay a fine of 135 euros (US $154.7).

"That is because we note that there are worrying signs of resumption of the epidemic in certain places of the national territory," Health Minister Olivier Veran told France Info radio early in the morning.

Since the lifting of lockdown on May 11, health authorities have detected between 400 and 500 active coronavirus clusters resulted mainly from family meetings during the summer holidays, the minister added.

"We are noting dynamic virus circulation which worries us and which must worry French people. They are the ones who hold the key (in the fight) against the virus," said Veran.

He, however, stressed that "at this stage we are far from a second epidemic wave."

"We must remain vigilant, prepare, explain..." he added, noting that "all the scenarios are not only being studied, but completed."

In June, the scientific council that advises the French government on COVID-19 detailed four scenarios of future epidemic situation based on acceleration of virus spread and increasing of tension in hospitals, with recommendation of measures to be activated in response.

The first scenario describes an "epidemic under control" as a result of nearly two-month lockdown. The second is "the appearance of critical clusters" in which the government should reinforce testing, quickly isolate cases and trace suspect ones.

The third scenario consists of a "progressive, quiet restart of the epidemic, which would be more difficult to control" and the fourth -- the most severe -- a "critical degradation" in the situation leading to a "loss of control on the epidemic," which likely will force authorities to re-impose restrictive rules on people movement.

Nationwide the "R" number indicating the viral transmission rate now stands at 1.2, up from 0.6 per cent in the previous weeks. That means 10 infected people will infect an additional 12 on average, according to the Public Health Agency.