The Sri Lanka Navy has seized more than 168kg of Kerala cannabis in seas off Thondaimanaru.
The Navy said three suspects were arrested while a vessel was seized.
The suspects had attempted to throw the sacks overboard and escape upon the arrival of the Navy.
The 168kg of Kerala cannabis was stored in 75 packages.
The street value of the seized stock of Kerala cannabis is believed to be over Rs.50 million.
Meanwhile, in another operation three suspects were arrested in the Ippantivu Lagoon with 650kg of dried turmeric stored in 21 sacks.
The three suspects have been handed over to the Customs Preventive Office in Sinnapadu, with the consignment of contraband for legal action.