Police seized 31 kilogrammes of heroin from the Karachi Cantt Station on Thursday.
The heroin was found in a case of guavas on a Pak Business Express train during a search operation.
The train had travelled from Lahore to Karachi.
According to reports, the case was put on the train in Rohri, a town in Sukkur.
Police and Rangers arrived at the scene and the bilty number of the package has been found on a goods delivery note.