The public prosecutor in French Polynesia says nearly another 100 kilogrammes of cocaine has been found on a sailing boat seized in the Tuamotus last week.
The boat was first searched on behest of the customs department after it docked on the atoll of Apataki and 340 kilogrammes of the drug was found.
It was then transferred to Tahiti where more concealed drugs were recovered, bringing the total haul to 436 kilogrammes.
The boat had sailed from Panama and was crewed by four men - three Italians and a Peruvian.
The four are being held in Papeete and are at risk of being jailed for 30 years and incurring fines of nearly $US10 million.
The prosecutor said the dimension of the case is such that it will be passed on to a specialised international agency in Paris.
Since 2016, there have been six major seizures in French Polynesia of drug consignments emanating from Latin America and destined for the western Pacific.