The estimated number of flu cases -- including swine flu -- in France has reached epidemic proportions, according to preliminary data released Wednesday.
"Last week the number of visits to doctors for flu in mainland France was estimated at 52,300, which is to say 83 cases per 100,000 inhabitants," said the National Institute for Health and Medical Research (Inserm).
The threshold for declaring an epidemic is 80 cases per 100,000.
"We will have to see the same figures for a second week to confirm that the threshold has been passed and confirm the start of an epidemic in France," Dr Thierry Blanchon told AFP.
Not all the cases have been confirmed as flu, and not all are the new A(H1N1) virus, a global pandemic which the World Health Organisation says has killed 2,837 people around the world since it emerged in April.
Inserm said it was hard to be sure to what extent the extra consultations -- there were 45,500 more visits to the doctor last week than in the same period last year -- were linked to swine flu panic rather than actual cases.
If confirmed, an official health warning could be issued next week.
Paris authorities for the first time shut down for seven days a primary school in the French capital after three suspected swine flu cases were reported in one class on Wednesday.
There have also been school and class closures in the Paris region and in the southern Aude and Lot regions and in Ariege, in the southwest.
In all, 19 people have died in France from the H1N1 virus but only three on the mainland. There have been seven confirmed deaths from swine flu in New Caledonia, six in Polynesia and three in the Indian Ocean island of Reunion.