The Engineering, Printing & Manufacturing Union says coal miners want independent inspectors in mines who can raise the alarm at the first sign of trouble.
The Department of Labour suspended operations at Solid Energy's Huntly East mine on Wednesday after a build-up of methane gas was discovered.
The department lifted a prohibition on mine development on Friday, but won't allow coal extraction to resume until it is assured that ventilation throughout the mine is working.
The EPMU wants Solid Energy to introduce check inspectors elected by union members, and that be a legal national requirement.
It says companies can be torn between increasing production and the safety needs of their employees.
Solid Energy says check inspector systems have more negative than positive effects.
The company believes all mine employees should take responsibility for safety.
Solid Energy says industry safety improves faster when everyone involved commits to it.