Chinese shares tumbled more than three percent in the morning session on Tuesday amid weak economic data, suggesting the world's second largest economy faces mounting downward pressure.

As of 10:15 a.m. (local time), more than 1,000 shares across the two bourses sank, Xinhua reported.

The stocks in textile machinery, automobile manufacturing and the steel industry reported the morning's biggest losses.

China's manufacturing purchasing managers' index (PMI) came in at 49.7 in August, down from 50 for July, according to the data released on Tuesday morning by the National Bureau of Statistics and the China Federation of Logistics and Purchasing.

The August reading was the lowest since August 2012.