Shipments of steel products by China reached the highest-ever last month as mills in the biggest producer turned to overseas markets to make up for falling demand in the oversupplied domestic industry.

Exports were 8.52 million metric tons, up 73 percent from a year earlier and 9.8 percent from August, according to data from the country’s customs administration today. Outbound shipments in the first nine months of 2014 rose to 65.3 million tons, up 39 percent from a year ago, the data showed.

Steel prices in China, which produces almost half the world’s steel, fell more than 15 percent this year due to an overcapacity and falling demand at home. The price of iron ore, a key ingredient for steel making, slumped 40 percent this year and touched a five-year low last month.

“Steel mills looked to the overseas markets as an outlet for its products as the industry was mired in an overcapacity and weakening domestic demand,” Zheng Yuesheng, a spokesman at the customs agency, said today at a briefing in Beijing.

China’s steel demand may deteriorate in the fourth quarter from the previous quarter as spending on infrastructure and property slows and some steel traders face tighter financing, Zhang Hai, vice president at Hebei Iron & Steel Corp., China’s largest steelmaker, said Sept. 25. Crude steel output climbed 5.4 percent in the first eight months in 2014 to 550 million tons, National Bureau of Statistics data show.

Iron ore imports rose 13 percent to 84.69 million tons in September, the highest since January and the second-most on record, customs data showed. Steel products imports rose 16 percent to 1.36 million tons.

The spot price of steel reinforcement-bar, or rebar, used mostly in construction, declined 17 percent this year to 2,957 yuan a ton.