BEIJING, Oct. 13 -- China's producer price index (PPI), which measures costs for goods at the factory gate, went down 2.8 percent year on year in September, the National Bureau of Statistics (NBS) said Sunday.

On a monthly basis, the PPI edged down 0.6 percent, narrowing from a 0.7-percent decrease a month earlier, the data showed.

NBS statistician Dong Lijuan attributed the monthly PPI performances to fluctuations in international commodity prices and insufficient effective demand in the domestic market.

From January to September, the average PPI decreased 2 percent from a year ago.

The consumer price index, a main gauge of inflation, was up 0.4 percent year on year in September.