The incident occurred in the Arles Central House, a high-security prison designed for inmates with long sentences and those considered to have little chance of social reintegration.
"The Prison Supervisors' Union is astonished at the disconcerting attitude with which the inmate was able to escape so easily and questions the usefulness of the Central House", the union said in a statement released late on Sunday.
The SPS specified that the exit permission was granted to the convict, who has yet to serve 8 years in prison, to "sign papers," adding that sufficient security measures have not been provided before granting the leave. The inmate was accompanied by only two officers and without handcuffs.
The union said the escapee was still on the run, shedding light on the poor security management in the prison and urged measures be taken to catch the fugitive.