Employees of ArcelorMittal Montreal were locked out on Thursday night by the global steel giant after they rejected the company's last contract offer.
The company said in a statement Thursday it was "forced" to take the action.
Fifty-two per cent of 262 workers present voted against the contract Wednesday night, saying they objected in particular to proposed changes to the company pension plan.
The employees, who work in Contrecoeur, northeast of Montreal, also insisted the wage increases being offered were insufficient.
The company locked them out shortly afterward.
Union didn't strike
ArcelorMittal said it offered employees a 13 per cent wage increase over five years. Acceptance of the offer would have raised the average annual salary to $68,000, it added.
Union spokesman Guy Gaudette said he was surprised by the lockout because the two sides had been involved in a recent negotiating blitz with a mediator.
The union had also not exercised its strike mandate.
Gaudette says ArcelorMittal wanted to move from a fully funded pension plan to a defined contribution plan for younger workers and future employees.
While the company would take care of the contributions in both cases, the pension amount for employees in the new plan would depend on its performance over the years.
Gaudette said that would make it more difficult for young workers to plan for retirement.
The company also deplored acts of vandalism it said took place after the lockout started.
"These regrettable and unacceptable acts have jeopardized the safety of the people present and caused significant material damage," the company said in its statement.
The 300 unionized workers have been without a contract since July 31. The company makes leaf springs and steel frames for the auto and construction industries.