A police officer said that acting on a tip-off, a truck was intercepted at Tawngtaimual Zemabawk near Aizawl.
Heroin concealed in 200 soap cases was recovered from the vehicle.
The 16-year-old helper of the truck driver, a resident of Assam’s Hailakandi district, was arrested in connection with the seizure, the police officer said.
The seized heroin, vehicle and the detainee were handed over to Bawngkawn police station for further investigation and legal action.
The heroin was smuggled from Myanmar.
A case has been registered under the NDPS Act.