Several people have been taken in for questioning in the New Caledonia mining town of Kouaoua, which has been the scene of arson attacks this year.
The public broadcaster reported the arrests shortly after the French High Commission affirmed its intention to station about 20 armed police in the town permanently.
Last week, three people 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 High Commission said the exasperation by Kouaoua residents and SLN employees was legitimate in the face of actions which nothing could justify.
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.
TV reports said there had been a rally in Kouaoua to protest against the lawlessness by some young people accused of setting fires.