Medawatte said inmates at Mahara Prison had completely destroyed the kitchen, the hospital, a newly built rehabilitation building and vocational training facilities.
The prison housed 4,100 inmates, about four times its capacity, an issue common across the country’s jails.
In July, the authorities announced plans to convert disused state buildings into prisons.
More than three-quarters of the inmates in Sri Lanka are remand prisoners awaiting trial, and most are held in connection with drug offences.