An inmate of the Hindalga Central Prison was admitted to hospital after he was stabbed by another in Belagavi on Saturday night.
Sai Kumar, an undertrial from Mandya district, was seriously injured when Shankar Bhajantri, a convict, stabbed him with a screwdriver.
The tool, it is said, was obtained by Bhajantri from the carpentry training section inside the jail.
A case has been registered.
Jail Chief Superintendent Krishna Kumar has ordered an inquiry.