About 500 workers at Potash Corporation of Saskatchewan's Allan, Cory and Patience Lake operations began a strike on Thursday evening, after the company was unable to reach an agreement over contracts with members of the United Steelworkers union.
The employees concerned were responsible for underground mining operations, as well as milling and shipping activities on the surface, Potash Corp said.
The strike was called after no resolution was reached during four days of mediation, and after a 12-hour strike was held last week at the Cory mine.
The workers, who have been without contracts since April, argue that they should also receive some of the additional profits being earned by the company as a result of surging potash prices and government incentives.
“The company simply refuses to move away from the offer that our members soundly rejected," said United Steelworkers Western Canada director Stephen Hunt.
"The company is making enormous profits, and it is time to reflect those profits with fair wages, pensions and benefits...in other words, share the wealth.”
Potash Corp president and CEO Bill Doyle has described the company's offer, which it says would raise pay by between 27% and 35,6% over a three-year contract, as "final".
He argued that the profits being enjoyed by the company were being reinvested into its operations, which had a positive impact on surrounding communities, and pointed out that the group was Saskatchewan's biggest taxpayer.