China's factory-gate inflation fell to its slowest pace in 20 months in September due to a drop in prices of commodities such as crude oil, official data showed on Friday.

China's producer price index, which gauges factory-gate prices, increased 0.9 percent from a year ago in September, following a 2.3 percent rise in August, the National Bureau of Statistics said.

On a monthly basis, the PPI fell 0.1 percent in September, narrowing from a 1.2 percent decline in August.

China's consumer price index, a main gauge of inflation, rose by 2.8 percent year-on-year in September, following a 2.5 percent rise in the previous month, the NBS data showed.

Compared to a year ago, food prices increased 8.8 percent, against a 6.1 percent gain in August, resulting in a rise of around 1.56 percentage points in headline CPI. Notably, pork prices jumped 36 percent on a yearly basis, compared with a 22.4 percent increase in the previous month. 

On a month-on-month basis, the CPI increased by 0.3 percent after a 0.1 percent decline in August.

The growth in core CPI, which excludes volatile food and energy prices and is deemed as a better gauge of the supply-demand relationship in the economy, came in at 0.6 percent year-on-year in September after a 0.8 percent rise in the previous month.