It's the worst crisis to hit the French prison system in 25 years, as a strike by wardens enters its ninth day. Officers are protesting over staff levels and violence inside the country's overcrowded jails.
Unions have rejected a government proposal to employ 100 extra guards this year and a further 1,000 over the next four years.
The unions say the system needs a complete overhaul.
"We need to re-examine the entire force and this needs to be done coherently, not just add temporary personnel that we'll lose in four years," said Thibault Capelle, a member of the Force Ouvrière union at Fleury-Mérogis prison. "Our profession must be made attractive. The police did it and now it's time it's done in the prison system. "
Unions claim 115 of France’s 188 prisons are blocked, while prison authorities put the figure at 50.
France's prison population has more than doubled since the 1970s, and prison guards complain increasingly that they have neither the staff nor the equipment and support to deal with violent inmates.