"We were calling for some slowdown, but the degree is much more than what we expected," said Jeff Ng, chief economist for Asia at Continuum Economics, a research firm.
Over the weekend, a private survey showed growth in China's factory sector stalled after 15 months of expansion, with export orders falling the fastest in over two years, while an official survey confirmed a further manufacturing weakening.
The official manufacturing index fell to a seven-month low of 50.8 in September, from 51.3 in August and below a Reuters poll forecast of 51.2. That index has stayed above the 50-point mark for 26 straight months. A reading above 50 indicates expansion, while a reading below that signals contraction.
But the Caixin/Markit Manufacturing Purchasing Managers' Index (PMI) fell more than expected to 50.0 in September, from 50.6 in the previous month. Economists polled by Reuters had forecast 50.5 on average.