At Senate Estimates yesterday, Coal Mining Industry (Long Service Leave Funding) Corporation chief executive Darlene Perks confirmed that six of the eight cases raised last year by Senator Roberts contained "discrepancies" and "administrative errors" in which the numbers of hours worked by casual mine workers were "under reported". This resulted in workers accruing less leave than they should and the corporation being paid less than it should in levies to fund the industry's long-standing portable leave scheme.

Ms Perks said that "as a result of what [Senator Roberts] had told us", Coal LSL would work with its "independent auditors" to "help them better understand certain areas", especially the hours logged by employers for casuals, and the related levies.

She said Coal LSL would now go back through its files to 2010 to look for other discrepancies.

Senator Roberts first raised his concerns at senate estimates in October last year, airing grievances over the use of "sham casual" contracting at Muswellbrook's Mount Arthur mine, and other coal mines across NSW and Queensland. He said thanks should go to injured and sacked Mount Athur/Chandler Macleod "casual" Simon Turner, who had "battled, battled, battled, just to get someone to listen".

Asked what progress Coal LSL had made since October, Ms Perks said the organisation was "in discussions continually with Chandler Macleod and Mr Turner" and would use its powers to subpoena documents from the company if it needed to.

Senator Marise Payne - who represented the Attorney General, Angus Porter, at the October sittings - was back again yesterday, telling Senator Roberts she had been "concerned about the matters raised" by Mr Turner and others and that she was "happy to indicate I will continue to work you on that".

In an earlier hearing yesterday involving members of the Attorney General's Industrial Relations Group, Senator Roberts raised the broader issue of what he called "deliberate, blatant and egregious . . . wage theft" that involved firms such as Mount Arthur's BHP in "being able to engineer substantially lower than award rates through sham contractors".

In response, Senator Roberts was told that it was up to "the firm and the bargaining representatives" as to what an agreement "looked like" but that agreements signed off by the Fair Work Commission were by definition "lawful".

Departmental deputy secretary Martin Hehir said the Fair Work Ombudsman had been given $10 million in funding to investigate deliberate "sham contracting", and there were penalties against companies if the offence was proven.

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