France, April 27 -- The UFAP-UNSA union announced on Monday that staff across dozens of facilities could walk out in protest at chronic overcrowding and a deepening staffing crisis - two issues that have been steadily intensifying for months.

Officials working inside prisons, from frontline guards to senior directors, have repeatedly warned that conditions are deteriorating fast.

Those concerns were amplified in January when the Council of Europe issued a stark assessment, criticising French prisons as overcrowded and often unsanitary, and cautioning they risk becoming little more than "human warehouses". A detainee is pictured in his prison cell at the "Maison d'arret" (prison) des Hauts-de-Seine, in Nanterre, suburbs of Paris, on...