Unions have pulled the trigger on worker strikes to choke BHP’s sole WA iron ore port, marking the most severe industrial action taken in WA’s mining industry for a generation.

Between 160 and 200 unionised workers at BHP’s Port Hedland operations will down tools for eight continuous hours next Thursday.

A trio of unions — the Electrical Trades Union, Australian Manufacturing Workers Union and Australian Workers Union — are behind the drastic move after their latest round of pay talks with BHP broke down on Tuesday.

The unions’ have refused to reveal their pay demands, but want significantly more than the 16 per cent wage increase over four years that BHP successfully offered to 1814 workers at its key South Flank and Mining Area C iron ore mining hub last week.

AMWU WA state secretary Steve McCartney on Wednesday labelled that South Flank and Mining Area C deal as “undercooked”, despite majority workforce support.

It is understood that the work stoppages at Port Hedland will keep rolling on if BHP does not cave in to the union demands.

BHP could lose more than $120 million in revenue a day if its exports grind to a halt. And WA would be deprived of about $6.85m in iron ore royalties for each day of a total shutdown, equivalent to the annual salaries of 50 senior nurses.

Electrical Trades Union WA secretary Adam Woodage indicated that the stoppage could “very well” put a block on BHP’s exports.

“Does this eight hour stoppage potentially have an effect on ships being loaded? I would go as far as to say it may very well,” he said on Wednesday.

“This is nobody’s preferred way forward, but when it is our only way forward, we will take it.”

Port Hedland is Australia’s number one iron ore port. It is used by BHP, Fortescue, Mineral Resources and Gina Rinehart’s Roy Hill.

In an internal email obtained by The West Australian, BHP Port Hedland general manager Dan Mossman said he was “disappointed” by the industrial action escalation.

“We are disappointed the unions have decided to take this step, particularly after two further meetings were proposed for Tuesday 14 July and Tuesday 21 July and agreed to by the unions at our eighth bargaining meeting yesterday,” Mr Mossman stated in his email to staff.

“The unions’ statements today about a lack of progress in bargaining doesn’t reflect what is actually happening at the bargaining table.

“You may be aware that two weeks ago BHP tabled a draft agreement and a pay proposal, and in yesterday’s meeting we continued discussions about how we could align our remuneration structures in a way that’s fair and equitable for everyone.”

Mr Woodage’s ETU has waged a war on BHP as part of a broader campaign by the union movement, spurred on by Federal Labor’s pro-union policies, to re-establish a strong foothold at Pilbara iron ore mines after decades on the sidelines.

About 40 high-voltage network workers aligned with the ETU began industrial action, mainly encompassing bans on overtime, across BHP’s iron ore mines in March. It marked the first such action at a Pilbara mine in more than 30 years.

Mr Woodage on Wednesday said those overtime bans would likely be escalated to full-blown work stoppages for the same eight hour duration, and on the same date, as the port strikes.

Premier Roger Cook said he did not support a major disruption to BHP’s operations but wanted the mining major to reach a “good negotiated outcome”.

Chamber of Minerals and Energy WA chief executive Aaron Morey said the escalation at Port Hedland was “deeply disappointing” but “does not come as a surprise”.

“Union leaders have signalled all along that they are itching to bring strikes and division back to the Pilbara,” Mr Morey said.

“Since 2000 – after unions left the Pilbara – iron ore production has grown five-fold, creating more than 55,000 jobs on mines paying some of the highest wages in the country.

“Now the industry’s ability to continue attracting investment is at serious risk. The Pilbara became a global success story because people focused on getting the job done, not picking fights.”