The operation was carried out Monday by a joint task force of Indonesia's National Narcotics Agency, customs officials and Riau Islands police after authorities received intelligence about a vessel allegedly transporting narcotics from Malaysia's Sarawak state toward Indonesian waters, said Roy Hardi Siahaan, the National Narcotics Agency's director of enforcement.
Indonesia is a major hub for drug trafficking in Southeast Asia despite having strict drug laws.
Convicted smugglers are sometimes executed by firing squad.
Siahaan said authorities intercepted the Tanzania-flagged MV Ocean Porter in waters off Tanjung Parit in Bengkalis regency, Riau province, and towed it to a customs operations base on Batam island, next to Singapore, for inspection.
Investigators believe the vessel previously operated as the MV Rain Maker, altering its identity to evade detection.
He said investigators found approximately 2.6 tons of liquid methamphetamine hidden inside eight drums and the vessel's water tanks, describing the seizure as "one of the largest drug busts in Indonesia this year".
At a Batam port news conference, authorities paraded the 10 crew members, all Myanmar nationals, in restraints.
"The crew and evidence remain under intensive investigation as authorities work to identify and dismantle the international trafficking network behind the shipment," he said.
Monday's seizure came less than two weeks after authorities intercepted the MV King Sun off Bintan island and confiscated 1.3 tons of ketamine, in one of Indonesia's largest narcotics busts.
Eight crew members, including seven Myanmar nationals and a Taiwanese citizen, were detained in that operation, which followed a three-month multinational intelligence investigation involving Thai authorities.
Siahaan said his agency has warned that Indonesia's vast coastline and proximity to major regional shipping routes make its maritime borders vulnerable to transnational drug smuggling.
He added that military and law enforcement agencies would continue joint operations to disrupt international trafficking networks.
The United Nations Office on Drugs and Crime identifies Indonesia as a major drug-smuggling hub, driven in part by international syndicates targeting its vast young population.
Last year, Indonesian authorities arrested 285 people suspected of drug trafficking, including 29 women and seven foreigners, and seized over half a ton of narcotics during a two-month crackdown.
About 530 people, including 90 foreigners, are on death row in Indonesia, mostly for drug-related crimes, the Ministry of Immigration and Corrections' data show.
Indonesia's last executions, of an Indonesian and three foreigners, were carried out in July 2016.
