The man, whose name has not yet been released, was in a cherry picker when the incident occurred just before 9am.

Police said the contractor was in the cabin about 15m off the ground when he was crushed by an overhead metal structure.

Emergency services were called to the mine, which is operated by Boggabri Coal – a wholly-owned subsidiary of Idemitsu Resources Australia – at 8.50am.

Colleagues are understood to have worked to keep the unconscious man, who suffered severe head and neck injuries, alive until paramedics arrived.

However the man, aged in his 30s, went into cardiac arrest and could not be revived. 

Paramedics pronounced him dead at the scene.

Police established a crime scene and inspectors from NSW Trade and Investment’s mine and safety investigation unit were dispatched to the site.

The man was working on Thiess-Sedgman’s joint project to construct a $180 million coal handling and preparation plant on behalf of Boggabri Coal at the time of his death.

In a statement, his employers said: “Thiess and Sedgman extend their deepest sympathies

to the employee’s family and full support is being extended to them.”

Idemitsu Australia Resources released a statement yesterday afternoon announcing all mining would cease at the site until further notice.

“Idemitsu Australia Resources is co-operating fully with NSW Police and workplace authorities as they investigate the incident,” a spokesperson said.

“Our main priority is the family and workmates of the person involved and we will work closely with our construction contractor to provide the appropriate support and assistance at this time.”

NSW Resources and Energy Minister Anthony Roberts also expressed his sadness at the tragedy and promised “a full and detailed report will be prepared for the coroner”.

“My thoughts and prayers are with the family, friends and community affected by this tragic accident,” he said.

All workers at the coalmine are understood to have been offered trauma counselling.