China's official purchasing managers index (PMI) for the manufacturing sector slid into economic contraction territory in May.

The manufacturing PMI declined for the second consecutive month in May and stood at 49.4, versus 50.1 in April, said the National Bureau of Statistics on Friday.

A reading above 50 indicates expansion, while a reading below reflects contraction.

"Production activities continued to expand in May, while demands slackened somewhat," Zhao Qinghe, a NBS senior statistician, said in a note.

China's non-manufacturing PMI stayed unchanged from the previous month and stood at 54.3 in May, registering the fifth month in a row with a reading above 54.

The composite PMI, which covers manufacturing and non-manufacturing activities, edged down to 53.3 from April's 53.4, indicating an overall steady expansion in economic activities, according to the NBS.