BEIJING, June 9 -- China's producer price index (PPI), which measures costs for goods at the factory gate, went down 4.6 percent year on year in May, the National Bureau of Statistics (NBS) said Friday.

The decrease expanded by 1 percentage point from that in April. On a monthly basis, China's PPI went down 0.9 percent, according to the bureau.

Dong Lijuan, a statistician with the NBS, attributed the decline to an overall downward trend in international commodity prices, weak demand in domestic and foreign industrial product markets, and the high comparison base during the same period last year.

The average PPI in the first five months of the year dropped 2.6 percent from the same period last year, according to the NBS.

The PPI for the oil and gas extraction industry lost 19.1 percent year on year, and that of the ferrous metal smelting and pressing industry fell 16.8 percent from the same period last year.

Bucking the trend, the PPI of production and supply of electric power and heat power sectors rose 1.6 percent year on year, while that of textile and garment industries went up 1 percent year on year.

The carry-over effect of last year's price movements contributed about 2.8 percentage points to the year-on-year PPI decline in May, compared with 2.6 percentage points in April, Dong said.

Friday's figure also showed China's consumer price index, a main gauge of inflation, edged up 0.2 percent year on year in May.