A 22-year-old man has died in custody at Maghaberry Prison, the Northern Ireland Prison Service has confirmed.
No details about the inmate or the circumstances surrounding his death have been revealed.
The young man died at the high-security facility near Lisburn on Thursday morning and his next of kin have been informed.
The PSNI, Coroner and Prisoner Ombudsman have also been informed.
Ronnie Armour, Director General of the Prison Service, said: “On behalf of the Northern Ireland Prison Service, I would like to extend my sympathy to the family of the prisoner.
“My thoughts are with them at this difficult time.”