China's iron ore imports contracted last month, adding to evidence that a deepening slowdown in the world's second-biggest economy is hurting demand for raw materials.

Inbound cargoes fell 14 per cent to 74.12 million metric tons from 86.1 million tons in August, which was the highest level this year, according to customs data Tuesday. Imports for the first eight months declined 0.2 per cent to 613 million tons.

After decades of rapid growth and an unprecedented expansion in steel production, China is now grappling with excess capacity as a property-led slowdown crimps demand. Iron ore prices tumbled in July to their lowest in at least six years as surging low-cost output from Rio Tinto Group in Australia and Brazil's Vale swamped the market. Deadly explosions at Tianjin port last month also disrupted shipments and may have reduced the import figure, according to Shenhua Futures Co.

"The latest trade figures probably bore out the impact from the Tianjin blast though the effect wasn't huge," Wu Zhili, a Shenhua analyst in Shenzhen, China said by phone. "China's weakening demand is the broader trend. Iron ore imports probably peaked last year so we'll see purchases sustained at current levels or slightly lower."

Ore with 62 per cent content delivered to Qingdao rose 1 per cent to a two-month high of $US57.42 a dry ton on Tuesday, according to Metal Bulletin Ltd. It sank to $US44.59 on July 8, a record low for the price dating back to May 2009.

The slowing economy and a weak property sector have hurt domestic steel demand, curbing output and iron ore purchases. Mills in the world's biggest producer are still making more steel than the economy needs as they benefit from cheap ore, Lourenco Goncalves, chief executive officer of Cliffs Natural Resources, said in an interview last month.

The surplus is spilling onto world markets. Steel-product exports were sustained in August around the highest since January, adding to a flood that has battered global prices. Outbound shipments were 9.73 million tons, 25 per cent more than a year earlier, according to customs. Exports in the first eight months climbed 26.5 per cent from a year earlier to 71.9 million tons.

Credit Suisse Group estimates that shipments were in line with total output from Japan, the world's second-largest producer. Exports may rise to 111 million tons in 2015, according to Macquarie Group's head of commodities research Colin Hamilton. Last year, the country shipped 94 million tons.

President Xi Jinping is trying to shift China from high-speed, debt-fuelled growth to a more consumer and services-driven economy. Steel demand in the country that buys more than two- thirds of seaborne ore will drop this year and next, according to the World Steel Association.

China's exports dropped 6.1 per cent in August in yuan terms from a year earlier, while imports plummeted 14 per cent, the statistics bureau said.