The Goro Nickel company in New Caledonia has stopped operations after vandalism on a massive scale over the weekend.
It is the biggest industrial enterprise under construction in the South Pacific with a planned investment of well beyond two billion US dollars.
An unidentified number of Kanak activists opposed to the nickel project have blocked roads.
A Kanak activist, Jaques Boengkih, says French police have fired on demonstrating Kanaks but caused no injuries.
Two police officers, however, are reported injured.
A company spokesperson, Catherine Guillaume, says police are still breaking up blockades.
"We have not finished yet to evaluate all the damages but we can tell you now it will be more than 100 million Pacific francs - two big excavators, more ten big mine trucks, pipes that are very expensive, lots of material, lots of equipment have been destroyed. We don't know exactly how much it will cost but in terms of material damage it is very, very high."