Growth in China's consumer spending continued to cool in September as the country's third-quarter growth was the slowest since the global financial crisis, new data has showed.

The country's retail sales rose 11.6 percent from one year earlier in September, the National Bureau of Statistics (NBS) said on Tuesday. The pace of growth has declined for four months in a row.

"The main culprit for the lower nominal retail sales growth was the decline in inflation. Adjusted for inflation, real year-on-year retail sales growth edged up compared with August, suggesting consumption remained stable," China International Capital Corporation, a leading investment bank, said in a report on Tuesday.

In the first nine months of the year, retail sales rose 12 percent year on year to 18.92 trillion yuan (3.08 trillion U.S. dollars).

Retail sales growth in rural areas outpaced that in urban China. In the January-September period, sales in rural regions rose 13 percent from a year ago to 2.6 trillion yuan, while sales in urban areas climbed 11.9 percent to 16.31 trillion yuan.

The bureau said online retail sales surged 49.9 percent from one year earlier to 1.82 trillion yuan during the period.

It also said per-capita average disposable income in China reached 14,986 yuan in the January-September period, up 10.5 percent year on year, or an increase of 8.2 percent in real terms after deducting price factors.

The country's GDP grew 7.3 percent in the third quarter, compared with 7.5 percent in the second quarter and 7.4 percent in the first quarter of this year.

NBS spokesman Sheng Laiyun said the growth stayed in a "reasonable range," with progress being made in restructuring.

Consumption contributed to 48.5 percent of China's economic growth in the first nine months, eclipsing investment, which accounted for only 41.5 percent, Sheng said.