There has been a major acid leak at New Caledonia's new Vale-Inco nickel plant into waterways while tests were being conducted at the new plant.
Thousands of litres of acid were spilled during incident which has killed nearly 2,000 fish.
The company had run the test although the system to contain a possible spillage was not yet operational.
The provincial government has strongly criticised Vale-Inco, with the WWF environmental organisation calling for the operating licence for Vale-Inco to be withdrawn.
The plant, which cost billions of dollars to build, is set to be inaugurated in the middle of this year.
Its construction was accompanied by delays and controversy as it is in an area of the New Caledonian lagoon which last year was awarded world heritage status.