A murder investigation is underway after a man died following an incident in Cloverhill Prison in Dublin.
Emergency services were alerted to the incident at about 05:30 BST on Saturday, gardaí (Irish police) have said.
It is understood there was a row in a cell involving three prisoners, according to Irish broadcaster RTÉ.
The man, who was in his 40s, received treatment at the scene but was pronounced dead a short time later.
It is understood he was from Ballyfermot in west Dublin and was known to gardaí for involvement in serious and organised crime.
A second inmate is being treated for injuries, which have been described as non-life threatening, RTÉ has reported.
Gardaí said they are investigating all circumstances surrounding the death and the scene has been preserved for full forensic and technical examination.
The coroner has been notified and the services of the state pathologist have been requested.
The Prison Service expressed its condolences and said that the death will be investigated by the office of the Inspector of Prisons.
