Chinese HSBC services PMI dropped to the lowest level since August 2011, falling to 50.9 in December from 52.5 in November.
The decline mirrors a drop in the official print to 54.6 from 56, as well a deceleration in manufacturing growth, and suggests that the slowdown in the economy is broad-based.
The sub-index for new business orders sank to a six-month low of 51.8, although labor conditions improved.
HSBC put a positive spin on the data, saying it expects that the expansion in manufacturing and that economic reform will support the services sector.
Still, the reading helped drag down Asian markets amid fears that China's slowdown will continue in Q1.
The Shanghai Composite -1.8%, Hang Seng -0.4%, Japan -2.35%, India -0.3%. (PR)