The four inmates are in remand custody over their involvement in heroin rackets.
Police said an individual who instigated the protest has been arrested.Police officers have been deployed to the prison to ensure the situation is brought under control.
Secretary to the Ministry of Defence, Maj. Gen. (Retd) Kamal Gunaratne has instructed the Inspector General of Police (IGP), C.D. Wickramaratne to probe into the tense situation escalated at the Mahara Prison on Sunday (29), the Ministry of Defence said in a statement issued today (30).