China's producer price index (PPI), which measures costs for goods at the factory gate, fell 2.1 percent year on year in September, the National Bureau of Statistics (NBS) said Thursday.

The decline slightly widened from the 2-percent drop in August, the NBS data showed.

Month on month, the PPI rose 0.1 percent last month as industrial activities perked up and market demand further improved, said NBS senior statistician Dong Lijuan, adding that the prices of industrial products continued to increase.

Prices in the ferrous metal mining and dressing sector went up 1.3 percent, while prices in nonferrous metal smelting and rolling rose 0.7 percent, according to the NBS data.

Dong also said that due to price fluctuations of international crude oil, prices of oil-related industries reversed the upward trend, with prices in oil and natural gas extraction shrinking 2.3 percent last month from August, and those for the processing of oil, coal and other fuel declining 0.5 percent.

In the first three quarters, factory-gate prices were down 2 percent on average from the same period last year, according to the NBS data.

The PPI data came along with the release of the consumer price index, which rose 1.7 percent year on year in September, easing from the 2.4-percent rise registered in August.