Government Railway Police (GRP) on Friday seized 3.5 kg opium from a suspect here on Friday.
The illicit substance was recovered from the possession of a 40-year-old man in Guwahati.
The suspected person was coming from Dibrugarh station and was headed to Coachbihar station, when he was apprehended.
A case has been registered under Narcotic Drugs and Psychotropic Substances Act (NDPS) Act. An investigation is underway to unearth more facts.