Corporate sales fell for the first time in three years in the July-September quarter, pressured by China's economic downturn and dips in petroleum product prices, government data showed Monday.

Combined sales of domestic companies dropped 2.6 percent from a year earlier to ¥349.50 trillion ($3.19 trillion), following a 0.4 percent rise in the previous quarter, according to the Finance Ministry.

Among manufacturers, telecommunications equipment and metal product sectors were the worst performers in terms of sales, affected by a slowdown in China's economy on the back of its trade dispute with the United States, a ministry official said.