The Canadian Auto Workers (CAW) union has requested the Canadian Government to probe Xstrata's plans to shut down the Kidd Mine copper and zinc metallurgical facilities in Timmins, Ontario, on 1 May.
CAW wants the Canadian federal and provincial governments to initiate an investigation into the Xstrata's decision to close the plant at the Kidd Creek mine.
CAW is opposing the closure as it could lead to 4,428 job cuts, C$152m ($142m) losses in annual taxes, and C$237m ($221m) losses in annual wages, according to a study by the Timmins Economic Development Corporation.
In the Timmins area, 1,162 jobs are expected to be cut, which translates into C$54.5m ($50.9m) in lost wages.
CAW president Ken Lewenza said that north-eastern Ontario cannot afford to lose such highly productive jobs.
Xstrata plans to move production from Kidd to Quebec-based smelters and refineries.
The CAW said if the probe concludes that Xstrata has little reason to shut down the Timmins site, both levels of government must force Xstrata to sell their Timmins assets.