New Caledonia's SLN mining company says a complaint has been lodged with police after its mining site in Thio was vandalised on Sunday.
SLN says nobody was injured in the incident but says installations were set on fire and trucks damaged.
It puts the damage at 1.3 million US dollars.
Police are now investigating.
It is not known what prompted the disturbance.
Despite the damage, work has resumed at the mining site, which is on the main island's eastern coast.