A 31 year old inmate of Mid North Coast Correctional Centre was taken by road ambulance to hospital about on Monday following an incident.
About 1pm, paramedics were called to the maximum security facility at Kempsey, after reports of an alleged stabbing.
According to a Corrective Services NSW Spokeswoman, “the maximum-security inmate is believed to be suffering from a collapsed lung and is in a stable condition”.
Three inmates, aged 27, 28 and 35, have been identified as persons of interest.
NSW Police have been notified.