French naval forces have detained three Vietnamese boats caught fishing beche de mer illegally in northern New Caledonia.
The public broadcaster said the so-called "blue boats" were spotted by a surveillance aircraft off Belep and by local fishermen inside the Ouvea lagoon.
The report said two of the three boats had been caught before.
The three vessels were being routed to Noumea where they will be prosecuted for illegal fishing.
Two weeks ago, the naval forces released four Vietnamese boats after seizing seven tons of beche de mer caught illegally.
A senior French official said he wondered how, and where, these small blue boats were refuelled to be able to be at sea for so long.