Fortescue Metals Group Ltd has been ordered to improve its safety procedures by the mines regulator following the death of a man at its Christmas Creek mine.
The 23-year-old contractor was carrying out maintenance on a surface miner, a large piece of mining machinery, in the Pilbara mine's heavy vehicle workshop when the accident occurred overnight on Monday.
It is the second death at the iron ore mine in less than five months.
The West Australian Department of Mines and Petroleum (DMP) has issued special directions ensuring that Fortescue tightens safety procedures at all of its operations, including lock out/tag out procedures, ahead of a safety audit in the new year.
Surface mining operations at Christmas Creek have been suspended as DMP inspectors carry out a site investigation.
"The inspectorate has so far determined that a number of recent incidents at Fortescue Metals Group mine sites appear to have involved an ineffectual isolation and lock out/tag out process," State mining engineer Simon Ridge said.
"This may or may not be a contributory factor in this most recent incident."
He said the legal directions would remain in place until Fortescue could ensure lock out/tag out procedures were effective.
Staff at Christmas Creek have been offered chaplains and other counselling services following the man's death.
His name is yet to be released by police.
Unions are concerned the company's efficiency program is being prioritised over safety.
CFMEU Construction Division WA secretary Mick Buchan said his union had received complaints about safety concerns at Christmas Creek in recent months, including anonymous emails from workers who were worried about identifying themselves.
"We want the full gamut of potential contributing factors to be examined in detail, including potentially unsafe working hours on site, the capacity of unions to access the site to assess safety, the replacement of experienced workers with cheaper alternatives – the lot," Mr Buchan said.
He said the death was a huge alarm that something was wrong on the site.
"We need to get to the bottom of it quickly and accurately before anyone else is killed or hurt."
Fortescue said another worker had suffered leg injuries in the incident.
The man's death comes 4.5 months after electrician Kurt Williams, 24, was crushed to death while carrying out maintenance work on a large motor in the crushing plant at Christmas Creek.
Mr Williams' death broke a two-year fatality-free run at Western Australia's mines.
At the time, Electrical Trades Union WA secretary Les McLaughlan said the union had raised concerns about safety practices and specific concerns about the kind of work Mr Williams was undertaking.
In October, truck driver had his leg amputated after being crushed at the Christmas Creek mine.
Earlier this month, a contract construction worker Stephen Hampton was killed at Newcrest's Telfer gold mining operations when a large piece of pipework rolled onto him.