SYDNEY, Jan 29 (Reuters) - Australia's Port Hedland was officially closed earlier on Friday following warnings from the weather bureau that a tropical cyclone was developing off the northern coast, Pilbara Ports Authority said in a statement.
Port Hedland, which handles about a fifth of the world's seaborne iron ore trade, is used by BHP Billiton (L:BLT) BHP.AX and Fortescue Metals Group FMG.AX , with the lion's share of shipments headed for Chinese steel mills.
Port of Dampier will also officially close at 1000 GMT, Pilbara Ports Authority said on its website.
"The ports will reopen when the cyclone has crossed the coast, and once authorities give the all clear," it said.
The Australian government's Bureau of Meteorology on Friday said Tropical Cyclone Stan had formed north-northwest of Port Headland in Western Australia.
The cyclone was expected to strengthen to category-2 on Saturday with "destructive winds", the bureau said.
Earlier, business daily The Australian reported that BHP was evacuating workers from its Port Hedland export facilities following the weather bureau's warnings.