Western Australia's mineral-rich Pilbara region braced Friday as powerful Cyclone Damien prepared to make landfall, causing ports to close and forcing mining firms to stand down non-essential staff.

Damien is already a category three storm and is expected to bring winds of up to 230 kilometres (140 miles) per hour as it strengthens to category four and touches the coast near the town of Karratha, population 16,000, early Saturday.

A spokesperson for Rio Tinto told AFP the company had "started the process of demobilising non-essential people from our sites which may be affected by the weather system."

The region is the centre of Australia's world-leading iron ore trade, and home to mining giants Rio Tinto, Fortescue and BHP, which was also reportedly reducing operations.

Key ports at Walcott, Dampier, Ashburton and Hedland have also been cleared as strong winds made mooring dangerous.

The Bureau of Meteorology warned residents of "very destructive" winds and heavy rain that is likely to cause flooding.