Ports in Australia's resource-rich Pilbara region stopped loading on Sunday as an intensifying tropical cyclone approached. Cyclone Christine is expected to reach the coast late on Monday.
Cape Lambert and Dampier ports, which are used by Rio Tinto, as well as Port Hedland, used by BHP Billiton and Fortescue Metals, closed to shipping and sent all vessels out to sea as the storm neared. The three ports handle more than 500 million tonnes of iron ore annually, accounting for almost all of Australia's exports.
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The Australian Bureau of Meteorology said the cyclone, which had intensified to Category 2, was 365 km (226 miles) north, northeast of Port Hedland on Sunday afternoon. It was moving southwest at 10 km (6 miles) an hour toward the Pilbara coast.
"If Christine continues to develop as expected a severe tropical cyclone impact on the Pilbara coast is likely late on Monday or early on Tuesday, with very destructive winds with gusts in excess of 165 kilometres per hour (102 mph) near the cyclone centre," the bureau said.
The storm off Australia's northern coast threatens to bring mining and oil and gas production to a standstill.
The three largest iron ore miners were watching closely and making preparations.
"The mine and rail operations continue to operate as normal but ship loading has now stopped," Rio Tinto spokesman Bruce Tobin said in a statement.
BHP spokeswoman Fiona Hadley said the company was "progressively securing port, rail and mine infrastructure and tying-down equipment".
Fortescue Metals said it was preparing in line with its cyclone procedures.
The northwest is also home to two of Australia's biggest gas production facilities, Woodside Petroleum's Northwest Shelf and Pluto liquefied natural gas (LNG) plants.
While declining to say whether production facilities had slowed or staff had been moved, Woodside spokesman Daniel Clery said the company was "taking all necessary steps to safeguard its people and assets".
Australia is the world's largest producer of iron ore and exports from Port Hedland were 28.1 million tonnes in November, just off October's all-time peak of 29.0 million and 29 percent higher than in November last year.
The majority of the ore is shipped under contract to steel mills in China.
Australia can expect an average cyclone season running from Nov. 1 to April 30, with up to 11 storms. Cyclones are categorised from 1 to 5, with 5 being the most severe and bringing wind speeds of more than 280 km (175 miles) per hour.