All staff at the Koniambo nickel smelter in New Caledonia's north have been evacuated after a spill at one of the furnaces.
New Caledonian radio says nobody was injured in the incident.
Firefighters have been at the scene.
This comes just four days after a blast at the site prompted a brief interruption to operations.
The Koniambo plant was officially opened by the French president, Francois Hollande, last month although it started nickel production last year.