Unions push on with strike at BHP's Port Hedland

"On the second day, on Sunday, all three unions are going to be walking off the job for 24 hours," McCartney said in the state capital Perth, according to an audio recording.

A spokesperson for BHP, which ships some $80 million worth of iron ore daily through the facility, said, "Vessels are being loaded, with scheduled departures subject to usual port planning and tides", adding in an email: "Our focus remains on reaching a fair and reasonable agreement."

The three unions of the Combined BHP Ports Unions, representing a portion of BHP's workforce at the port of more than 800 people, are negotiating a four-year bargaining agreement with the world's third-largest iron ore miner. They opted to go ahead with the strike despite progress in talks between the parties on Tuesday.