Detectives are investigating a stabbing at Goulburn Correctional Centre's Supermax on Sunday.
A 29-year-old inmate, reported to be Talal Alameddine, the brother of alleged underworld boss Rafat Alameddine, was cut on the shoulder and face, during what police described as a "physical altercation" with a 21-year-old prisoner in the jail's recreational area.
Alameddine was taken to Goulburn Base Hospital on Saturday for treatment of minor stab wounds and lacerations.
The younger man was uninjured.
Detectives from the State Crime Command's Criminal Groups Squad and the Hume Police District are investigating further as is Corrective Services.
A Corrective Services spokesman confirmed the altercation occurred within the High Risk Management Unit, known as Supermax, at 11am.
The department declined to supply further details. A spokesman did however say that no officers were involved and the facility did not go into lockdown as a result.
It's understood Alameddine returned to the prison on Sunday afternoon.
It follows another stabbing at the facility's maximum security area in July, 2020. At that time, a 31-year-old inmate was stabbed in the neck with what was believed to be a jail-made weapon after an altercation with a 21-year-old prisoner. He suffered minor, non-life threatening injuries and was flown to Canberra Hospital for treatment.