(Yicai Global) Oct. 9 -- China's Caixin Purchasing Managers' Index for services fell to 50.6 in September, down 2.1 points from the month prior to mark the lowest value in 21 months.

The figure contradicts data from the official PMI, which was more positive at 54.4 and up 1.8 points on the month.

China has two key purchasing managers' indices. The official PMI is run by the state and comprises 3,000 companies, most of which are state owned, whereas the Caixin index, often known as the Caixin-Market index, reaches out to 500 businesses which are generally smaller and privately owned.

The Caixin data puts the comprehensive PMI for September at 51.4, down by 1 point to the lowest figure for three months.

The official manufacturing PMI came in at 52.4, up 0.7 point from August and considerably higher than the Caixin manufacturing PMI of 51, which fell 0.6 point to end a three-month rise.

The Caixin PMI reflects fine economic performance in the third quarter, said Zhong Zhengsheng, chairman and chief economist if CEBM Group, a subsidiary of Caixin Insight Group, which runs the Caixin index. However, the depression of manufacturing and services indices last month may imply a continued decline into the fourth quarter, he added.