An ALS worker has been dismissed and the police called in the wake of the investigation, which found that as many as half the certificates of analysis were amended without justification.

Terracom CEO Danny McCarthy said some of the company's customers also asked for additional coal samples to be tested, and in every instance, they found no quality control issues.

"During my time as CEO of Terracom there has not been an occasion whereby clients have complained about the quality of the coal as certified by the Certificate of Analysis," he said.

Under the certificate of analysis process, each time a ship is loaded the testing company carrying out the coal sampling and analysis takes samples and divide them into three lots.

These include a control sample tested for the issuance of the COA that forms the basis of the certified result for the buyer and invoicing and payment purposes; a buyer's sample sent to the customer for its own internal sampling and checking; and an umpire's sample held in reserve under full chain of custody requirements and "seal" by the testing company for a pre-determined period. That way there is an umpire sample available should either the seller or the buyer need it.

"In the one recent instance where a customer requested three shipments be ‘Umpire tested' at a third-party laboratory, the umpire results aligned and were consistent with the certified results used for the basis of invoicing and payment," McCarthy said.

Terracom has also categorically denied allegations made in court by its former commercial general manager Justin Williams that it was involved in a scheme relating to the "fake analysis of coal samples".

According to the company, Terracom and the six directors who have been named as individual respondents will vigorously defend the proceedings that have been started in the Federal Circuit Court.

"Each of the six directors are seeking for the proceedings to be summarily dismissed on the basis that none of them had any knowledge or involvement in Mr Williams' termination," it said.

"Mr Williams was made redundant in August 2019. This was the month after he started employment with the company and while he was still in his probationary period.

"It was subsequent to his redundancy that Mr Williams falsely alleged that Terracom altered reports about the quality of its coal exports."

Terracom said it was unaware of any regulatory investigation into Williams allegations.

"Mr Williams' allegations were made only after he was dismissed as part of a company-wide redundancy program," it said.

"Terracom and each of its directors, reserve their rights to take legal action against any party that publishes false or misleading information based on Mr Williams' allegations."