Environmentalists in New Caledonia are planning a demonstration against the lack of legal action for last April's acid spill from the Vale nickel mining plant.
The leak killed thousands of fish and affected the World Heritage protected Prony Bay during a test run of Vale New Caledonia's new facility.
Marina Kahlemu of the environmental group Corail Vivant says locals are also angry about an incident last week in which a worker was burnt by acid at the plant.
Noumea's daily newpaper reported the 54-year old was flown to Sydney for treatment.
Ms Kahlemu says a mass gathering of environmental groups and local people is planned outside the offices of the South Province authorities which has been under fire for delaying the legal process.