PARIS -- After banning gatherings of over 100 people and closing all nurseries and schools, France on Saturday announced a countrywide shutdown of all non-essential public places in a fresh move to halt the spread of the novel coronavirus.

Warning "an acceleration of the virus spread, and an increase in the number of people in intensive care," French Prime Minister Edouard Philippe ordered the closure from Saturday midnight and until further notice all non-necessary businesses, including shops, restaurants, cinema, bars and discos.

Only food stores, pharmacies, banks, petrol stations and tobacco shops will stay open. Public transport networks will operate. Places of worship would stay open but all services and ceremonies would have to be postponed.

Philippe urged the French to "absolutely" limit their movement, avoid inter-city travel and strictly respect the guidelines of distancing.

"Facing a virus which is rapidly spreading, we decided to step up measures which hit social life," he said, noting that too many people were still out in the streets and not sufficiently respecting barrier gestures recommended by health experts.

"We must all together show more discipline to apply these measures. We must avoid gathering as much as possible, limit friends' and family gatherings," stressed the prime minister in a joint briefing with Director-General of Health Jerome Salomon.

As of Saturday, coronavirus infection cases in France doubled to 4,500 in 72 hours, of which 91 died. 300 patients are now hospitalized in intensive care, half of whom below 60 years of age, Salomon announced.

France now move to "stage 3", the highest emergency level of its epidemic response plan, which requires reinforced measures to reduce the pandemic impact.

Under France's epidemic response plan adopted in 2011, the authorities' objective in stage 3 moves from "slowing down the spread" to "attenuating the effects of the epidemic wave".

Since entering stage 2 on Feb. 28, the French authorities had vowed to mobilize all necessary preparations before the transition into the highest alert stage, which they expected to delay as long as possible.

Stage 3 marks the end of individual monitoring of cases by the Health Watch Institute. In case of saturation of the health care resources, treatment priorities must be applied, according to the 2011 epidemic response guide.