The New Caledonian Kanak Rheebu Nuu and Caugern groups say they may take further action against the region's biggest industrial project, Goro Nickel, if it does not halt all construction work.
They initially said they will take action by September the 24th if construction work continues because the project is failing to meet the required environmental standards.
But they now say they may take action earlier because the company received its first shipment of pre-fabricated components, that will be used for the construction of the plant, this week.
A spokesperson for Caugern and the Kanak USTKE union is Pierre Chauvat.
"The modules have been transferred to the plant, but the effective construction has not taken place yet. We have warned the Southern province not to start building the plant, because we could go into actions more quickly than we thought."
Goro Nickel spokesperson, Catherine Guillaume, says the company is not worried about possible action, as the site is protected by local gendarmes.
Ms Guillaume also says the company will continue to seek dialogue.