A key index showed a slowing expansion in non-manufacturing industries in May.

The purchasing managers' index hit 54.3, down from 54.5 in April, the National Bureau of Statistics and the China Federation of Logistics & Purchasing reported on Monday.

Growth in new orders almost flatlined in May as seen by a reading of 50.1, the lowest level since November 2011. Service businesses saw new orders contract for the second consecutive month to 49.2 in May, compared with 49.8 in April.

On Monday, HSBC released the manufacturing PMI for May - 49.2, an eight-month lows reported by the NBS on Saturday.

"There was no meaningful improvement in China's manufacturing sector in May," said Sun Junwei, an economist at HSBC.

"Policy makers continue to face a tough challenge in striking an appropriate balance between the need to push through structural reforms versus the need to preserve near-term growth."