Hudbay Minerals Inc. (TSX:HBM), which has operations near Flin Flon and Snow Lake, says in a news release that 180 members of the International Association of Machinists and Aerospace Workers Local No. 1848 began a strike at noon Saturday.
The company says the striking workers represent about 12 per cent of its 1,460 person workforce in Manitoba.
The union has said members want changes in wages and pensions.
It says 96 per cent of its members voted against an offer from the company last month.
Hudbay says it has a contingency plan in place and expects its operations to continue.
"Hudbay sought a mutually negotiated agreement over several months and does not believe the strike action is necessary," the company said in the release.
The union said on its website last month that one of its main objectives was to reduce the gap between apprentice and certified trade wage rates. It said it also wanted issues such as grievance procedures and contracting out addressed.
It said members were left with no other option but to strike.
"We offered to assist management with a controlled shutdown of all operations in the event a strike, but they rejected this offer outright," union representative Ian Morland said in a news release on Thursday.
"They believe they can run the equipment without us. But we repair and maintain this equipment and it will break down if it is not maintained properly. This could have been avoided," he added.
Hudbay produces zinc, copper, gold and silver.
Hudbay spokesman Scott Brubacher said last month that the company's offer was generous — a wage increase of nearly 11 per cent for certified mechanics, pipefitters and machinists, a ten-per-cent hike in the pension, plus an improved benefit plan.