The momentum of the manufacturing sector showed signs of wearing off in July, raising concerns over an economic slowdown.

The purchasing managers index (PMI), a comprehensive gauge of industrial activity, eased 0.9 percentage points from a month earlier to 51.2 percent in July, said the China Federation of Logistics and Purchasing.

A reading above 50 points indicates expansion, and it has stood above 50 points for 17 straight months. However, the index is down for the third consecutive month and is at its lowest since February 2009, when it fell below 50.