Hundreds of workers at Muswellbrook's Mount Pleasant coal mine walked off the job for three days this week after a colleague was injured on the site.
The Australian Manufacturing Workers Union says the man needed surgery after tearing a muscle from the bone of his upper arm in a rigging accident.
However, management allegedly decided against seeking medical help for the worker and opted to take him to his accommodation to rest instead.
A union official drove the man to hospital.
Fairfax reports the mine's owner has confirmed the incident took place but says the lack of first aid and safety systems was an issue for the contractor, G & S Engineering.
