Three men, including two expatriates, are in police custody in Oro province after marijuana was found in their possession.
Defence Force officers last Saturday rounded up the three men after they collected some of the dried marijuana leaves.
A crew member of a boat, reportedly from Rambucho village, Manus province allegedly threw some of the leaves into the sea, when sighted by the officers at Oro Bay wharf.
The three men are believed to be a villager and two Philippine expatriates of a Lae-based boating company.
They arrived in the province after their vessel was hired in Lae by some locals to travel to Popondetta.
Oro provincial police commander Snr Insp Samuel Jamangu confirmed the report and said the men were being detained for further interrogation.
The boat is being kept at the wharf awaiting the outcome of police investigations into the case.
Mr Jamangu said the crewman had admitted to having in his possession the drug.
He said some dried leaves were also found in a bag during a second search on the boat by the officers.
Mr Jamangu said he was waiting for statements from his officers and the PNGDF officers before possible charges could be laid.
He said the crew faces possible drug related charges as he had admitted to having possession of the drug.