A total of five coal-laden trucks were intercepted and seized in Salbari in Assam's Baksa district on Saturday, reports said.
As per information received, the authorities in Salbari intercepted the trucks en route from Sivasagar to neighboring Bhutan.
The trucks were loaded with coal with no paperwork, sources said.
The seized trucks bear registration numbers PB29L9792, AS01PC9529, AS02E5827, AS04BC8607 and PB13AR7363.
Following the incident, the truck drivers were detained, reports said.
Meanwhile, an investigation has been launched into the case and a heightened security has been maintained at the Salbari police station.