Tongan police have begun working with their Vanuatu counterparts in investigating the luxury yacht, the Phocea.
The boat was seized in Port Vila last month amid allegations involving drugs, weapons and the use of fake Vanuatu passports.
Radio Tonga says it was told that while the mega yacht was in Nuku'alofa, a luncheon was hosted and attended by government leaders and MPs.
It says following a complaint about unusal activities, the vessel was searched in Nukualofa and cleared by customs officials.
However, Tongan authorities are yet to establish how a Tongan national Maikolo Tangatalakepa got onboard.
He was among the passengers in Port Vila but Radio Tonga says he had last been in Nukualofa in 2006.
Radio Tonga also says 10 people arrived in Tonga by plane to board the yacht, including the reported owner, Anh Quan Saken, and five women from Serbia and the Philippines.
There is an information blackout in Vanuatu and the country's only officer trained to investigate fraud and international crime, Andrew Kalman, has been suspended.