BHP bracing for strike after WA workers back industrial action

Unionised workers at BHP's Port Hedland operations have voted in favour of industrial action. (ABC News: Charlie Mills)

450 workers at BHP's Port Hedland operations are expected to back protected industrial action, in a move that could halt ships from the worlds biggest bulk export port.

Unionised maintenance workers at BHP's port operations in WA's Pilbara have voted to go on strike, marking the start of what could be the mining industry's most significant industrial action this century.

The Australian Manufacturing Workers Union (AMWU) confirmed 90 per cent of its members at the mining giant's operations in Port Hedland, 1,600km north of Perth, backed the proposed work stoppages.

The Electrical Trades Union confirmed 100 members had unanimously backed their ballot late on Thursday.

The vote means stoppages involving up to 450 workers could begin as early as next week with staff required to give five days' notice of any industrial action at the country's largest bulk export port.

The ballots asked workers to endorse an unlimited number of stoppages, ranging between 30 minutes and 24 hours.

The votes covered 450 members of the ETU and AMWU in the port town. (ABC News: Jesmine Cheong)

The vote followed months of failed negotiations between the unions and BHP over a new employment agreement for its local workforce.

In a statement released after the vote, AMWU State Secretary Steve McCartney said the result was a sign of frustration within the mining giant's workforce.

"Workers shouldn't have to wait seven months for genuine progress at the bargaining table," he said.

"Members have had enough. They are demanding to be heard and they are demanding a fair agreement."

Mr McCartney urged BHP to respect the workers' decision and return to the negotiating table in good faith.

A BHP spokesperson told the ABC the company's focus was on reaching an outcome that maintained "industry leading pay and conditions".

Any industrial action will have a significant operational impact on BHP. (ABC News: Kimberley Putland)

Western Australia's Chamber of Minerals and Energy said union demands threatened to damage the national economy.

"Direct and cooperative bargaining has delivered decades of jobs and productivity growth, the highest average wages in the country and more than $100 billion in royalties for WA," Chamber chief executive Aaron Morey said in a statement.

"Shutting Port Hedland Port would cost our State millions in royalties per day, which erodes Government's ability to support nurses, teachers and other public servants.

BHP exported 290 million ton