Coal LSL chief executive Darlene Perks and general manager, legal, Peter Kembrey, gave evidence remotely to the committee, facing questions from One Nation Senator Malcolm Roberts and Labor Senator Deborah O'Neill.

Responding to Senator O'Neill, Mr Kembrey said Coal LSL knew of 78 employees "who we have recognised service for, who are unable to access their entitlements because their employers hold a contrary view".

"But we suspect there would be potentially hundreds of other employees of those organisations that cannot benefit the long service scheme benefits," Mr Kembrey said.

Senator O'Neill had demanded to know "how many hard working Australian men and women" were missing out on coal industry long service "because of some confusion in the government's non-advanced legislation to clean it up".

The Coal LSL executives defended the operation and integrity of the fund, with Ms Perks saying it had been given a clean bill of health by the Australian Audit Office.

She and Mr Kembrey explained some of the workings of the fund in relation to casual and contract mining employees, following questions from Senator Roberts that referred back to injured former Mount Arthur mineworker Simon Turner.

Mr Kembrey said that "as we discussed in March, we have been helping Simon for some years", but it was not their role to mediate a dispute between Mr Turner and his employer.

Referring to the disputed long service leave records of eight workers raised by Senator Roberts at the previous March estimates hearings, Ms Perks said the records of six had been amended, while two had remained the same.

Ms Perks described the portable coal industry fund as "the most generous" of its type because members could leave the industry for up to eight years and still retain their leave allocations.

Questioned by Senator Roberts, she confirmed that casual coal industry workers could agree to "waive" their long service accruals, and be paid an extra 2 per cent instead.

But she said that only four waiver agreements had been signed, as far as she knew, out of 426,000 records.

Ms Perks said employers paid a "tax" to the government of 2.7 per cent of wages for permanents and 2 per cent for casuals.

Working with actuaries, the pool fund was obliged to ensure it had enough resources to meet its obligations.

She said history had shown that a mineworker in their first year of service had a 49 per cent chance of working for the eight years needed to gain long service leave.

Those who left before eight years service - or who left the industry for more than eight years - would lose their entitlements.

Senator Roberts had questioned Coal LSL in last year's October sittings.

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