More job losses are expected in the NSW coal industry, with 100 positions at a major Hunter Valley coal mine on the chopping block.

The Construction, Forestry, Mining and Energy Union (CFMEU) has met with managers at the open-cut Hunter Valley Operations (HVO) coal mine near Singleton.

The mine is joint-owned by mining giants Yancoal and Glencore.

“They formally advised us they were going to make 116 jobs redundant,” CFMEU northern district president Peter Jordan told the ABC.

“The concern for us is that they advised us when they took over the job, Glencore, in May that they were doing a 90-day review and that they would sit down and have discussions with us about that.

“Well, 90 days haven't even come and here they are making this announcement, so there's a lot of angry workers on the job at Hunter Valley.”

It comes just days after Yancoal announced it would stand down or redeploy 200 employees from its Austar mine west of Cessnock, with the future of the operation in doubt.

Glencore says it simply does not need as many workers.

“The restructure follows a review by the HVO management team now operating the mine on behalf of Yancoal and Glencore,” the company said in a statement.

“The review has identified opportunities to reconfigure the operations, reducing the amount of equipment required.”

Mr Jordan said the union does not want redundant staff to be replaced by casuals.

“There is a high level of casual contractors in the workplace and there has been no indication by Glencore in their announcement this week that they'd be offloading the casual contractors,” he said.

“In fact, they're targeting the permanent production workers.

“I think this is about Glencore and Yancoal getting rid of permanent worker positions and replacing them in the long-term with further casuals, at a cheaper rate of pay.

“We experienced that with Glencore last year.”