BEIJING, Sept. 30 -- China's non-manufacturing activity maintained expansion in September, with the purchasing managers' index for the sector coming in at 51.7, the National Bureau of Statistics said Saturday.

The purchasing managers' index for the country's non-manufacturing sector came in at 51.7 in September, up 0.7 percentage points from a month earlier, the NBS data showed.

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

The sub-index for the service sector was 50.9 in September, up 0.4 percentage points from a month earlier, according to the NBS.

The service sector expanded at a faster pace during the period, NBS statistician Zhao Qinghe said, adding that business activities in water transport, postal as well as monetary and financial sectors stood well above 55.

The construction sector maintained brisk growth this month with its sub-index for business activities growing 2.4 percentage points to 56.2, Zhao noted.

The sub-index measuring expectations for activities in the sector came in at 61.8, indicating rather strong optimism among construction enterprises.

Saturday's data also showed that the PMI for China's manufacturing sector came in at 50.2 in September, bouncing back to the expansion zone.