Three more people have been charged in New Caledonia over the arson attacks at the mining town of Kouaoua.
The three were among seven people whom police had taken in for questioning earlier this week.
Last week, another three were arrested for the attacks on the installations of the SLN nickel mining company.
There have been 15 fires this year on the conveyor belt at Kouaoua which feeds ore to the coast for shipping to the SLN smelter in Noumea.
The French High Commission this week announced that it will station about 20 police around the mine.
The Kouaoua site, which provides more than a third of SLN's ore, was closed for nearly three months this year as a result of two blockades set up by a local group opposed to expanded mining.
The High Commission said the exasperation by Kouaoua residents and SLN employees was legitimate in the face of actions which nothing could justify.