Police have found 204 kilograms of cocaine and a badly decomposing body on a yacht that washed up in Tonga last week.

The drugs, valued at about US$116 million (NZ$123 million), were hidden in the hull, the Australian Broadcasting Corporation reported.

The 13-metre yacht JeReVe left Ecuador in August, laden with 204, 1kg blocks of cocaine which authorities believed were destined for the Australian market, the ABC said.

Contact with the vessel was lost on October 5. Australian police said it was found washed up on the isolated atoll of Luatafito a month later.

The Australian Customs Service believed two crew members were on board when the vessel left Ecuador.

Australian forensic pathologists have been sent to Tonga to help with the investigation and an autopsy was being conducted on the body.

Earlier Tongan police commissioner Grant O'Fee would only say that the yacht had been found.

"The yacht is being treated as a crime scene since a death occurred. Police at this stage have not ruled the death as suspicious but it remains an unexplained death," O'Fee he said.

O'Fee said that the body had not been identified and no cause of death established.

"But I can confirm that this man is not a Tongan national," he said.

- © Fairfax NZ News