There is a warning in New Caledonia that demonstrators could turn violent if the mining company, Goro Nickel, restarts work on its waste pipe.
A day of action is planned for Saturday against any further construction on the pipe which will dump waste into the lagoon.
Work on the pipe has been suspended since February but Goro Nickel wants to test the pipe between May and August, in order to start operations later in the year.
Our correspondent in Noumea, Claudine Wery, says it looks as though the protest will be peaceful but things could escalate.
"It should be a pacific demonstration because Goro Nickel suspended the installation of the pipe. But Rheebu Nuu and the Kanak leaders warn that young people were now ready to die for their environment if Goro Nickel wants to restart the installation of the pipe."
Claudine Wery in Noumea.