Maintenance workers at the Vale-owned Voisey's Bay mine have joined striking miners on picket lines. Maintenance workers at the Vale-owned Voisey's Bay mine have joined striking miners on picket lines. (CBC)

More than 50 maintenance workers at the Voisey's Bay nickel mine in northern Labrador have walked off the job, further complicating mine owner Vale's efforts to ramp up production.

About 200 miners at Voisey's Bay have been off the job since August.

Vale, known until last week in Canada as Vale Inco, has also been beset since last July by a strike of about 3,000 workers in Sudbury, Ont.

Vale returned to the bargaining table last week with United Steelworkers officials, in a bid to end the Voisey's Bay strike.

At the same time, Vale said it intended to increase production while the miners were still on picket lines.

"They've indicated they've wanted to ramp up production to full production — that'll be 24 hours a day, seven days a week," said Darren Cove, a Steelworkers official.

"Its going to make that more difficult where there's no maintenance on site to take care of the routine maintenance."

A Vale official said last week that the company was able to make only one shipment this winter from Voisey's Bay of nickel concentrate.

The maintenance workers are employed by Ushitou Maintenance, a contractor working for Vale at the mine site, and belong to a different bargaining unit than the striking miners.

The Steelworkers union said it is upset with the latest contract offer provided by Vale.

Miners at Voisey's Bay went on strike over company demands for a wage freeze and a rollback on bonuses.