The suspects made the disclosure during questioning by the Police Narcotics Bureau following their arrest in a joint anti-narcotics operation.
Investigators said the suspects had told officers that they departed from Galle Harbour on the 13th under the pretext of a fishing trip before allegedly receiving the drugs at sea.
During the operation, personnel from the Sri Lanka Navy intercepted the multi-day fishing vessel named Heshan Baba and recovered 103 kilograms of heroin packed in 91 parcels along with 913 grams of cocaine.
Six suspects who were arrested in connection with the haul were brought to the Dikovita Fisheries Harbour this morning for further investigations.
Authorities estimate the street value of the seized narcotics to be nearly Rs. 300 million.
The vessel and the suspects were taken into custody during a special naval operation conducted in the southern deep seas, and further investigations are continuing to determine the wider network behind the drug smuggling operation.