BHP Group Ltd said on Tuesday initial estimates indicated its iron ore production would take a hit of about 6 million to 8 million tonnes after disruption and damage caused by tropical cyclone Veronica last week.
The world's biggest miner said its 2019 financial year production and unit cost guidance are under review because of the cyclone which hit Western Australia.
BHP's 2018 iron ore output came in at 275 million tonnes and the company had set a production target of 273-283 million tonnes for fiscal 2019.
The miner said its port and rail operations in Port Hedland were currently operating at reduced rates and were not expected to return to full capacity until later this month due to flooding.
Port Hedland is also used by the world's fourth largest iron ore miner, Fortescue Metals Group Ltd, which last week said its port sites experienced minor flooding but its mining and processing operations were not affected.
Rio Tinto on Monday cut its 2019 outlook for iron ore shipments from the Pilbara region due to the effects of the cyclone.
(By Aby Jose Koilparambil; Editing by Sonya Hepinstall)