New Caledonia's Kanak Rheebu Nuu group has issued an ultimatum demanding that all construction work on the Goro nickel project stop before September the 24th.
The ultimatum was issued by the group's leaders, Andre Vama and Raphael Mapou, and communicated at a news conference in Noumea.
Mr Mapou says they have been manipulated by the Goro parent company, Inco of Canada, accusing the company of arrogance.
They say all work has to be stopped for fresh talks or else there will be what they call a war without mercy.
In April, Rheebu Nuu activists brought the two-billion US dollar project to a halt after vandalising Goro equipment worth 10 million US dollars.
The current Goro Nickel project was launched after the previous project was suspended in late 2002.
Rheebu Nuu says a possible third attempt to build the plant should have more of a local involvement.