China's producer price index (PPI), a major measure of inflation at the wholesale level, fell 6.6 percent in April year on year, the National Bureau of Statistics (NBS) announced Monday.

The decline compared with a 6.0-percent drop in March and 4.6-percent fall in the first quarter from the same period last year.

Prices of production materials fell 8.1 percent in April year on year, the NBS said in a statement.

The PPI for January-April fell 5.1 percent over the same period last year, it said.

The NBS also announced the consumer price index for April was down 1.5 percent year on year and 0.2 percent month on month.