French correction officials in New Caledonia are re-examining the territory's jail after a guard was beaten and briefly held hostage at the weekend.
A police spokesperson says he was kicked and punched in the head and kept in a cell for about half an hour before being freed by other guards.
The French High Commissioner told public radio that much work needs to be done to upgrade the facility.
The Camp Est jail is widely seen as one of the worst run by France, along the Nuutania prison in Tahiti.
The conditions at the prison have long been deemed unacceptable by expert missions sent by France.
Human rights organisations say the prison has poor sanitation and suffers from overcrowding.
In 2011, the European Human Rights Court condemned France for the way it jailed an inmate in New Caledonia.
