cyclone Ilsa
This satellite image taken by Himawari-8, a Japanese weather satellite, and provided by National Institute of Information and Communications Technology, shows cyclone Ilsa approaching Australia's west coast. Image Credit: AP

Sydney: A tropical cyclone smashed into Australia's northwest coast as a category 5 storm, setting new wind speed records, but has largely spared populated regions including the world's largest iron ore export hub at Port Hedland, authorities said on Friday.

Cyclone Ilsa made landfall early Friday morning with the highest intensity rating on a 1-to 5 scale and then moved inland as emergency crews urged several remote communities along the storm's path to seek shelter and remain indoors.

"Port Hedland ... escaped the brunt of the cyclone at this stage. Overnight, we received no calls for assistance," Western Australia state emergency services Superintendent Peter Sutton told ABC television. "So it appears the larger populated areas have really escaped the damage." But Sutton said there were unconfirmed reports of "extensive damage" at some remote towns and that an aerial survey would be conducted as soon as possible.

Port Hedland, used by miners BHP Group, Fortescue and billionaire Gina Rinehart's Hancock Prospecting, was scheduled to reopen at 11 a.m. (0300 GMT) after operator Pilbara Ports Authority deemed it safe.

In a statement, the operator said it is was liaising with terminal and vessel operators to plan out the resumption of shipping.

The port was closed on Thursday morning after authorities began clearing berths a day earlier.

Ilsa set a new preliminary Australian ten-minute sustained wind speed record of 218 km per hour (135 mph) at Bedout Island, about 40 km offshore, eclipsing cyclone George's 194 km at the same location in 2007, the Bureau of Meteorology said.

The storm was downgraded by the weather bureau to a category three system early on Friday, but officials warned it could still pack gusts of up to about 170 km per hour (106 mph).

"As it moves inland and the sun comes up, we can expect it to still be a severe tropical cyclone," the weather bureau's hazard response manager Shenagh Gamble said.

Ilsa is expected to weaken to a tropical low overnight and move into the southern parts of the Northern Territory.

Heavy bursts of rain are forecast in some areas, likely triggering flash floods. Destructive winds could hit the remote inland mining town of Telfer, where Newcrest Mining operates a fly-in-fly-out gold and copper mine.