India's coast guard has arrested six Myanmar men and seized $42 million worth of ketamine after spotting a suspicious vessel in the Indian Ocean near the Nicobar Islands.
The 1,160 kilogram (about 2,500 pounds) drug haul came after coast guard aircraft spotted the boat, which had its lights off, on Wednesday in India's Exclusive Economic Zone, the defence ministry said in a statement.
The boat's crew did not respond to radio calls and the coast guard eventually boarded it, with officials finding "57 gunny bundles of suspicious substance" on Friday.
"Preliminary analysis... revealed that the suspicious substance was ketamine and there were 1,160 packets of 1kg each onboard the vessel," the ministry added.
The six Myanmar men and cargo were taken to Port Blair, the capital of the Andaman and Nicobar Islands, where they were questioned by investigators.
They claimed they left Myanmar on September 14 and were due to rendezvous with another boat "operating near the Thailand-Malaysia maritime border line" on Saturday, the statement said.
The Nicobar Islands are located near Southeast Asia, off Myanmar's coast.
Parts of Myanmar, Laos and Thailand are in the lawless "Golden Triangle" zone, the world's second-largest drug-producing region after Latin America.
Large amounts drugs such as heroin and methamphetamine are churned out in remote jungle labs each year and smuggled across Asia and beyond.