MELBOURNE - Hundreds of workers at BHP's Port Hedland iron-ore operations in Western Australia could walk off the job next week, in what would mark the biggest industrial action there in decades, potentially disrupting $80-million of daily revenue for BHP.

The unions have called for the action, an eight-hour work stoppage set for July 16, after six months of negotiations that have failed to reach an agreement on terms for a four-year labour deal. The action is set to run from 2 pm to 10 pm (06:00 to 14:00 GMT).

Some 160 to 200 employees of the 450 workers who cover BHP's port and maintenance operations will walk off the job, according to the Combined Ports Unions, which represents four unions active at the site.

“This is nobody’s preferred way forward, but when it is our only way forward, we will take it," said Adam Woodage, the secretary of the Electrical Trade Union Western Australia.

“I hope this sharpens the minds of BHP managers - and shareholders - on the importance of negotiating for a fair, safe and productive iron ore industry.”

Union officials said a meeting with BHP was slated for Tuesday that could avert the stoppage.

The action comes after workers at some of BHP's other operations in the Pilbara region where Port Hedland is located narrowly voted last week to approve a new labour agreement.

“We have delivered a new enterprise agreement at Mining Area C and South Flank that rewards 1 800 workers -- without industrial action," BHP said in a statement on Wednesday.

“Every Australian benefits from a strong iron ore sector. We are eager to keep negotiating constructively for a fair deal, while making sure we can keep operations running safely.”

BHP shares fell 2.9% on the day to A$57.19 ($39.70), slightly outpacing losses among other miners and compared to a 0.5% decline for Australia's benchmark stock index.

Unions are making the biggest push in 30 years to penetrate Australia's mining heartland, emboldened by a Labor government law in 2022 giving them the power to negotiate wage deals that cover several employers, allow more scope to request flexible arrangements and industry-wide strikes.

The South Flank agreement last week included a guaranteed 16% pay hike over its four-year term, increases to site-based allowances and a new payment scheme for delayed flights.

"We think the South Flank deal is undercooked, for the work that they do away from their family and for the conditions," Steve McCartney, State secretary of the Australian Manufacturing Workers Union, told reporters. "Sixteen percent over four years is not enough."

Mining workers are among Australia's best paid. Resources workers living in the Pilbara earned A$191 000 on average in 2023/24, according to a survey by industry group the Chamber of Minerals and Energy.

Australia's median wage for registered nurses is A$85 000 to A$100 000 according to industry bodies and the median wage is A$75 000 a year, according to government figures.

Port Hedland, which is also used by miners Fortescue and Hancock Prospecting, ships around $150-million of iron-ore a day.