By James Regan

SYDNEY (Reuters) - Iron ore miners were waiting for conditions to ease before assessing damage caused by a cyclone that ripped across northwest Australia on Tuesday, closing ports and threatening mining operations in the sparsely populated Pilbara region.

The key shipping ports of Dampier, Cape Lambert and Port Hedland, the world's largest iron ore export terminal, bore the brunt of the storm after clearing dozens of iron ore freighters and evacuating staff over the weekend.

Reports of damage were not immediately available.

Cyclone Christine, the second to batter Western Australia state in the November 1-April 30 cyclone season, forced mining companies Rio Tinto, BHP Billiton and Fortescue Metals to suspend shipping until emergency authorities sound the all-clear, expected over the next day or two as the storm continues to weaken.

The majority of the ore is shipped under contract to steel mills in China.

"As Tropical Cyclone Christine tracks inland, Rio Tinto's coastal and West Pilbara operations remain closed," a company spokesman said.

"We are still fully assessing the impact at this stage. We are also focusing on the safety and wellbeing of our employees, their families and our Pilbara communities," the spokesman said.

A spokeswoman for BHP Billiton said it was too early to assess any damage because port and inland areas remained under Red Alert, making them inaccessible.

The region is also home to Australia's two largest liquefied natural gas (LNG) export facilities, Woodside Petroleum's North West Shelf and Pluto LNG plants.

Woodside said it had given employees at both facilities the all clear to return to work after evacuating non-essential personnel from both plants on Monday. The company declined to comment on any impact to production.

The North West Shelf and Pluto LNG plants have a combined capacity of over 20 million metric tons per year, around 85 percent of Australia's annual exports.

A red alert - meaning residents must seek shelter - remains in effect for Port Hedland and the mining hubs of Tom Price and Paraburdoo, according to the Australian Bureau of Meteorology.

"There is a threat to lives and homes," the Department of Fire and Emergency Services said in a statement. "You are in danger and need to act immediately."

Winds with gusts exceeding 130 kph (80 mph) are possible near the centre of the storm over the next few hours, but will ease as Christine moves inland, the weather bureau said.

About 56,000 people live in the Pilbara, which is about the size of Peru.

Top Australian supplier Rio Tinto, which is relying on Cape Lambert and Dampier to ship 290 million metric tons of ore next year, halted port activities on Sunday.

Exports from Port Hedland, used by BHP and Fortescue, reached 28.1 million metric tons in November alone.

(Additional reporting by Rebekah Kebede; Editing by Michael Perry)