The scandal has been ongoing since September, when an employee at Rio Tinto’s Coal & Allied Bengalla mine left a pornographic image of himself in his work computer, sparking a crackdown across all of the company’s mines.

Rio Tinto Coal Australia began the purge of company emails and computer files and subsequently sacked a number of employees from its Queensland and New South Wales mines, including workers from the Kestrel, Blair Athol, Bengalla and Tarong mines.

In September, a worker at Bengalla told the Newcastle Herald that 13 technicians had been "stood down indefinitely" for sending inappropriate emails.

“They look like losing their jobs, they were escorted off-site and told not to come back, so there's a lot of panic," he said.

“They were on $100,000 or $120,000 a year.”

He told the Newcastle Herald that pornographic emails were "pretty common".

A Rio Tinto spokesperson confirmed that some employees had been dismissed and that the inappropriate use of computers and emails within the company would not be tolerated.

The spokesperson said under company policy all employees were required to use its computers and email resources responsibly.

“Accessing, downloading or disseminating material which is offensive, sexually explicit, defamatory, discriminatory, racially or otherwise abusive, harassing or violent is regarded as a serious breach of this policy," she said.

“The policy is widely communicated to employees and abuses are regarded as misconduct. As a result of some serious breaches of policy, we have acted according to our disciplinary procedure."