The CSTNC strike in New Caledonia has entered its eighth week, but no efforts are being made to end the action.
The union has been pushing for the departure of foreign workers and cheaper living costs.
A Congress spokesperson says it is unlikely more talks will be organised because the union refuses to stop demonstrations and blockades when talks are scheduled.
The union is continuing to block one SLN mine and is hampering activity at another, while SLN's general manager, Pierre Alla, says its smelter in Noumea is operating at reduced capacity.
Mr Alla says SLN is losing about one million US dollars a day and may have to begin laying off some workers at the mines.
"The people who are affected by this measure are about one hundred people. I hope I will not have to do this lay-off."