Industrial action has started at BHP’s Port Hedland operations in Western Australia, marking the first major strike at the site in more than two decades. About 150 workers are expected to take part on Saturday, according to the Combined BHP Ports Unions, beginning with a 24-hour ship-loading ban followed by a 24-hour stoppage as the union negotiates a four-year bargaining agreement with BHP. The disruption affects only part of the port workforce of more than 800 people, and BHP has previously said it has plans to keep operations running. Port Hedland is the world’s biggest iron ore export hub, and BHP ships about $80 million of iron ore a day through it. Around eight ships are expected to finish loading from BHP ports over the weekend, a source familiar with the matter said. The action is not expected to affect Fortescue or Hancock Prospecting, which also use the port. Port Hedland handled 75% of total iron ore exports from Western Australia’s Pilbara region in the year to June. The dispute comes after more than seven months of talks over a new pay deal for around 450 operators and maintenance workers represented by the CBPU, against a backdrop of record share prices and rising living costs. The two sides are due to meet again on August 18, the same day BHP reports its annual results.