The CFMEU has accused BMA of attempting to bypass redundancy processes for the more than 200 workers it cut last month.
Last month the miner said a recent review of the mine determined staff numbers were too high, and began talks with employees on how to reduce numbers by 230 staff on site.
"BMA has made a number of changes across its operations to reduce costs and increase productivity in order to ensure that our operations are profitable and sustainable," BMA asset president Lucas Dow said.
"A recent review of the Saraji mine by the company concluded that a fundamental improvement in the cost base of the open-cut operation is required to ensure that it remains competitive."
At the time CFMEU district president Steve Smyth the union was disappointed to learn of the job cuts.
"Obviously we are disappointed that in the first instance there wasn't more dialogue about what the issues are," he told AAP.
"Now we want them (BMA) to comply with the agreement in regards to compensation."
Now Smyth is questioning the number of permanent workers cut, stating that “they’re still putting labour hire people on; they’re still putting contractors on,” the ABC reports.
"If it's a genuine redundancy requirement then that's fine, but there's been no evidence shown to us at this stage that's the case."
Smyth went on to say BMA have to justify the 230 redundancies.
"What we're saying is let's sit down and work through what the agreement requires where you've got to provide the documentation and evidence to say that many people have got to go."
These latest redundancies were a major blow for the region, which is still reeling from the decision to close the Norwich Park coal mine just over two years ago.