The figure is stable from month to month but up 4.7% year on year.
The number of detainees stood at 71,669 people on September 1 against 71,819 the previous month, according to statistics from the Ministry of Justice consulted on Monday by AFP.
Prisons had 72,067 inmates on July 1.
The slight drop in the number of people imprisoned over the past two months is recurrent in the summer period, due to traditionally slow judicial activity and thus fewer entries into detention.
With 60,715 operational places, the occupancy rate of the 188 French prison establishments now stands at 118% compared to 113.4% a year ago.
Huge overcrowding
This prison density is 139.7% in remand centers, where prisoners awaiting trial - and therefore presumed innocent - and those sentenced to short sentences are imprisoned.
Forty-eight prisons have a density above 150%.
This occupancy rate even exceeds 200% in four establishments (215.6% in Carcassonne; 205.5% in Nîmes; 201.5% in Foix and 200.3% in Bordeaux-Gradignan).
Because of this overcrowding, 1,830 prisoners in France are forced to sleep on mattresses placed on the floor.
Among the detainees, 18,986 are defendants, imprisoned awaiting trial.
They represent 26.5% of the prison population.
Alternative measures to incarceration
In a recent circular, the Keeper of the Seals Eric Dupond-Moretti asked prosecutors to "ensure the strict necessity of pre-trial detention" by favoring alternative measures to incarceration, such as house arrest with electronic monitoring.
A total of 86,243 were placed in custody as of September 1.
Among them, there are 14,574 non-detainees subject to placement under electronic bracelets (13,867) or placement outside (707), figures that are falling.
The number of female prisoners (3.5% of the total prison population) and that of minors (0.8%) are stable.
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Justice
French prisons still overcrowded despite a slight drop in the number of prisoners
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Prison overcrowding