Key Australia iron ore ports face short closure on cyclone threat

* Ships at 2 Australian iron ore ports face cyclone threat

* Ships being evacuated from Port Hedland, Dampier

* Ports authority anticipates relatively short closure (Adds forecast for duration of port closures)

SYDNEY, Jan 19 (Reuters) - Australia's Pilbara Ports Authority said it had started evacuation of ships at the Port Hedland and Dampier iron ore ports due to cyclone threat, but forecast a short closure due to the low intensity of the storm.

Any interruption in iron ore shipments from the key ports of top supplier Australia could support prices of the steelmaking raw material, which are mired near 5-1/2-year lows in a world market flush with supplies from big Australian miners.

Iron ore shipped via Port Hedland, which handles about a fifth of the world's seaborne iron ore trade, totaled nearly 40 million tonnes in December, most of which was mined by BHP Billiton and Fortescue Metals Group.

Depending on how close the system tracks the coast, gales may extend west to Dampier, used by Rio Tinto (Xetra: 855018 - news) to ship ore.

The tropical low pressure system is small and has the potential to develop rapidly, but due to moderately favorable conditions it is not expected to develop intensity above the lowest category rating, according to the Australian Bureau of Meteorology.

The Port Authority said it was anticipating a relatively short port closure as the storm is forecast to track parallel to the coast over the next 36 hours at a reasonable speed.

Evacuation of ships anchored near the ports commenced Monday morning at both ports, it said, adding that both ports expect the evacuation of ships in berth to be complete by the evening.

Last year, the Port Hedland Port Authority amalgamated with the port of Dampier, creating what it says will be the largest bulk export tonnage port in the world based in the Australian Pilbara iron belt.

Benchmark 62-percent grade iron ore for immediate delivery to China's Tianjin port stood at $68 a tonne on Friday, near a 5-1/2 year low of $65.60 reached in December. (Reporting by James Regan; Editing by Himani Sarkar)