The International Prison Observatory (OIP) said in a report that in 2022 “half the punishments decided by prison disciplinary commissions led to solitary confinement” — amounting to over 100,000 days.

This ran counter to recommendations from rights body the Council of Europe that solitary should be “imposed as a punishment  only in exceptional cases, and for a specified period of time, which shall be as short as possible”, it argued.

Such cells in France offer “inhuman” conditions with “furniture bolted to the floor, windows that barely allow light in, total isolation, one hour per day outside in a ‘walking courtyard’ with barely any view of the sky and no equipment” for exercise, the OIP said.

The body also denounced “numerous cases of violence and bullying by prison guards” reported both to the OIP and official oversight bodies.

Suicide attempts were 15 times more common in solitary than under regular detention conditions, the OIP said, citing a 2018 academic study.

Rights defenders acknowledged some progress, with judges able to check the decisions of prison authorities and lawyers allowed before disciplinary committees.

But they also pointed to an ever-growing list of punishable offences in prison — some of which they called “arbitrary”, including language on “maintaining order” or “normal functioning” of the jail.

Prisoners can be punished for minor offences including clothing judged improper, blocking peepholes into their cells or refusing to turn the volume down on their radio, the OIP highlighted.

The body called for measures including slashing the number of punishable behaviours in prison or offering an appeals process.

France’s prison population hit a new record of almost 76,000 people on January 1.