A tropical low system in the Indian Ocean off Australia's west coast was expected to develop into a tropical cyclone, Australia's weather bureau said, forcing the country's key iron ore exporting terminal to clear ships from harbor.

The Pilbara Ports Authority said in a statement late on Wednesday it had begun clearing large vessels from anchorages at Port Hedland, the world's biggest iron ore loading hub, and that ships were directed to sail by 1200 GMT.

Port Hedland is used by three of Australia's top four iron ore miners - BHP Group, Fortescue Metals Group Ltd. and Gina Rinehart's Roy Hill. Rio Tinto Ltd, the world's biggest iron ore producer, uses the nearby port of Dampier.

Australia's Bureau of Meteorology (BoM) said a Category 1 or 2 cyclone could make landfall on the Pilbara coast, possibly as early as Friday afternoon, bringing heavy rains, gale-force winds and huge seas. Although Category 1 or 2 cyclones are at the lower end of the scale, they still have the destructive power to delay port and mining operations.