An investigation continues into the response to a double fatality at the Mount Lyell copper mine.

New details have emerged about a WorkSafe Tasmania investigation in 2013, which was launched in response to the deaths of miners Alistair Lucas and Craig Gleeson.

Copper Mines of Tasmania (CMT) has reportedly been charged with failure to provide safe systems of work, following their response to WorkSafe's report.

The company faces up to $1.5 million in fines.

Media outlets this week claim to have seen copies of the WorkSafe Tasmania investigation and charge sheet issued by the Director of Public Prosecutions.

The WorkSafe report alleged says the men were in the process of repairing a linkage assembly on a heavy steel door, using a safety harness to build a temporary work platform.

But, reports say, the platform was built from king billy pine; a type of wood that could not support the loads placed upon it.

“The Mount Lyell Mine ... failed to ensure, so far as was reasonable practicable, the provision and maintenance of a work environment without risks to health and safety, the provision of maintenance of safe plant and structures, the provision and maintenance of safe systems of work,’ the WorkSafe report states, according to the ABC.

“There existed no design specification for the temporary wooden work platform,” the prosecution claimed, and the platform “was not affixed or secured”, it said.

The report allegedly said that WorkSafe believed Mr Gleeson had unclipped after building the platform to allow space for Mr Lucas to join him, Mr Lucas was not wearing a safety harness.

The prosecution argued that Gleeson was using a chipping hammer to open the linkage assembly, which fell and hit the wooden work platform, splitting it and causing the men to fall.

They fell 22 metres down a mine shaft, killing Mr Gleeson immediately while Mr Lucas later died in hospital.

The report alleges there was a lack of safety staff, standard designs for temporary work platforms and safe working procedures.

Furthermore, it allegedly says permits were not enforced and CMT could had records of the workers being trained in the task.

“It was reasonably practicable for CMT to have prevented the accident,” the report says, according to the ABC.

The Australian Manufacturing Workers Union says the mine should stay shut until a full safety overhaul in completed.

The case continues, with the next court date set for September 28.