China's official factory purchasing managers' index fell to 49.2 in August from 50.1 in July, the National Bureau of Statistics said on Saturday.
It marked the lowest reading since November 2011, in the latest sign that growth in the world's second-biggest economy is struggling against cooling exports, factory output and fixed asset investment.
Economists polled by Reuters this week had expected August official PMI to slip to 50, bang on the level that demarcates expansion from contraction.
A flash PMI published last week by HSBC plunged to a nine-month low of 47.8 in August, as new export orders slumped and inventories rose, a signal that a persistent slowdown in economic growth has extended deeper into the third quarter.
