Indian customs officials in the state of Assam have reported the largest-ever seizure of cannabis in the north-east of the country.
They say they have arrested six smugglers posing as border guards who were transporting 10 tons of cannabis.
Officials say the cannabis was being taken from Manipur to Madhya Pradesh.
Analysts say that tribal farmers are turning to planting cannabis because they make much more money by selling it than by raising other crops.
The joint head of customs in north-east India, K Ashi Kheiya, told the BBC he expected a 10-fold increase in seizures this year as a result of a sharp increase in cannabis production.
Correspondents say that substantial quantities of Burmese heroin and amphetamines are also coming into the South Asian market through India's north-east, particularly Manipur.