BEIJING — China's courier sector witnessed an expansion in August, the industry's monthly index showed.

The China express delivery development index stood at 357.4 in August, up 9.2 percent year-on-year, the State Post Bureau said.

The sub-index for development scale stood at 346.4, up 22.1 percent from a year earlier, while the sub-index for service quality stood at 630.8, up 7.7 percent year-on-year.

The express delivery volume is expected to grow 25 percent in September, according to the bureau's forecast.

Compiled on the basis of data from major logistics firms' operating delivery services, the development index reflects the overall business activities and trends in the country's courier sector.