The seizure was made when DRI officials checked the bags of four persons, including two women from Bhopal, who arrived at the Central railway station by the Tamil Nadu Express yesterday.
"Each bag had a false bottom in which about 1.6 kg heroin was found concealed in a polythene bag," a DRI release said today.
DRI officials identified and intercepted the kingpin, a person of Sri Lankan origin, who had come to receive the drug.
The total weight of the seized heroin was about 6.6 kg, the release said.
In related searches, packing materials used for the onward movement of the drug, the car used by the Sri Lankan national and Rs 4.3 lakh in cash were also seized, it said.
The arrested have been remanded to judicial custody, the release said, adding the value of the seized heroin is around Rs 10 crore in the international market.