About 900 employees at Rio Tinto Group’s aluminum smelting facilities in Kitimat, B.C. are on strike after Unifor Local 2301 and the company failed to reach an agreement on July 25.

The union continued negotiations with Rio Tinto until the strike deadline at midnight, according to a press release. Unifor is seeking changes to workers’ retirement income and benefit levels — including moving newer employees from the company’s defined contribution plan into its defined benefit plan — and demanding that Rio Tinto stops employing contractors and temporary employees outside of the agreement.

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“The difficult and demanding work our members do has made this facility a success for generations,” said Martin Mcllwrath, president of Unifor Local 2301, in the release. “We deserve nothing less than an agreement that respects us and we’ll stand up for our rights.”

In an emailed statement to Benefits Canada, Matthew Klar, chief media relations advisor for Rio Tinto, said the company is “committed to working with the union to reach a mutually beneficial outcome to the ongoing bargaining process.”