Iron ore up as Australian exports cut off Iron ore prices resumed their upwards trajectory after cyclones disrupted shipments from Australia, the largest supplier of the steelmaking commodity. The benchmark price of iron ore soared 82 per cent from a low in September to a 15-month peak of $158.50 a tonne a fortnight ago. It has since suffered a sharp tumble as buyers stepped back from the market ahead of February's Chinese New Year holiday. After a fall of 8.5 per cent from its peak, benchmark Australian ore with 62 per cent iron content rose 1.8 per cent in the past two days to $147.70 a tonne, the Steel Index reported. Iron ore is seen as a proxy for industrial activity and construction in China, which imports more than half of the world's seaborne trade for steelmaking. The commodity is critical for the profitability of large mining groups as well as the world's top steelmakers, including ArcelorMittal and Baosteel of China. The rally has been spurred by weather-related disruptions as the cyclone season closes key ports in Western Australia. Port Hedland, the world's most important iron ore port, was closed for about 24 hours while Rio Tinto's port operations at Cape Lambert and Dampier have also been forced to shut down as Cyclone Peta passed. Traders and brokers said China's steel mills returned to the market this week amid concerns that the cyclone season in Australia and Brazil could disrupt supplies. At the same time, steel prices in China have risen strongly, with April SHFE rebar for construction touching a six-month high of Rmb3,967 a tonne on Wednesday. "Iron ore markets continue to be supported by positive demand fundamentals," said Melinda Moore, a bulk commodity strategist at Standard Bank, adding that "steel inventories ­continue to be rebuilt ahead of the March construction season." Iron ore derivatives markets have witnessed a more dramatic shift in sentiment in recent days with the February SGX iron ore swap rallying 10.4 per cent in a week to $149.25 a tonne. The rebound in iron ore prices is a boon for the three big miners of the commodity: Vale, Rio Tinto and BHP Billiton. BHP Billiton shares rose 1.4 per cent on Wednesday as the company reiterated its guidance for a 5 per cent rise in iron ore production in the current financial year to June.