Negombo's Police Superintendent Venura Gunawardane said the suspect had been carrying on a drug business running into millions inside the prisons for some time. He said the prison officials searched the suspect after a tipoff and found 65 packets, each containing four grams of heroine, in his possession.
The SP said investigations had revealed that relatives who visited the suspect had smuggled in the heroin, concealed in food containers.
A prison official said the suspect was selling a packet of heroin at Rs. 25,000 or 30,000 inside the prison.
The suspect was to be produced before a magistrate yesterday. Investigations are continuing.