Unrest in Kone has left 11 police officers injured, one with a broken leg.
The unionists threw rocks while the security forces struck back with tear gas.
The violence followed a week-long protest which has seen the unionists cutting off access to the prefecture’s administration building and blocking the provincial road.
In Noumea, several business have again been blockaded, with some employers staging a counter demonstration.
This comes after a week of intermittent confrontations in and around the city as part of a campaign aimed at seeking the release of the jailed USTKE leadership.
The incidents are related to a labour dispute at the domestic airline.