Former Prime Minister, Malcolm Turnbull is calling for a New South Wales Parliamentary investigation into "inadequate" coal mine rehabilitation bonds.
This week's state budget included $108 million over the next ten years to remediate the state's disused legacy mine sites.
Most of the mines targeted were between 50 and 100 years old, but Mr Turnbull said the problem was more contemporary. "It's obvious the remediation bonds are inadequate," he said.
In NSW, a rehabilitation security bond must be paid by the mining company before exploration and production activities begin.
The security deposit covers the full cost of all rehabilitation and mine closure activities required if a mining company defaults on their rehabilitation obligation.