The prisoner who was stabbed to death at Wormwood Scrubs has been named by police as Saleh Khader.
A murder investigation has been launched after emergency services pronounced the 25-year-old dead at the scene in west London on Wednesday afternoon.
Four inmates were arrested on suspicion of murder after Khader's body was found with a number of knife injuries. The men, two aged 21, a 20-year-old and a 23-year-old, remain in police custody.
In a statement Scotland Yard said: "While formal identification awaits, officers are confident the deceased is 25-year-old Saleh Khader.
"A post-mortem examination will be arranged in due course."
The victim's next of kin have been told, police added.
It comes less than two months after a formal inspection of the jail raised concerns over chronic staff shortages, food shortages and a surge in violence.
Inspectors also found areas of the west London jail were strewn with litter, attracting rats and cockroaches, in what they said painted an “extremely concerning picture”.
