Owned by Wesfarmers Resources, the mine estimated to have coking coal reserve of 88 million tonnes and has an annual production capacity of 7 million tonnes.
Previously, around 70 labour hire workers were laid off by the company.
Earlier this month, 20 fulltime positions were also axed to reduce cost.
Thiess said that it took the decision in order to focus on sustainability in the face of a weaker coal market.
The Morning Bulletin cited an unnamed worker as saying: "We went to prestart on Thursday night to hear Thiess say they were laying off 50 labour hire personnel as of now.
"We finished our shift and next morning we were to ring the labour hire people to see if we still had a job.
"They’re (Thiess) not saying anything and all these people are stressed out… it’s got to the point where they can just say you’re not coming back tomorrow."
