The official Purchasing Managers' Index (PMI) edged down to 50.5 in January from December's 51, the National Bureau of Statistics said on Saturday, in line with market expectations.
The change reinforces concerns that China's economy is stuttering and could drag on financial markets on Monday as global investors, already nervous about capital flight in emerging markets, find another reason to sell riskier assets.
Emerging market stocks and currencies were sold off in the past week as investors cut financial bets in developing nations, in anticipation that the United States will continue to move to less easy monetary policy. Super-easy U.S. policy had spurred a flow of cash into emerging markets in recent years.
Saturday's PMI showed China's factories saw fewer export orders and slacker growth in new orders last month. A sub-index for new orders fell to a six-month low of 50.9, and export orders slipped to 49.3, also a six-month low and below the 50-point threshold separating growth from contraction in PMIs.
An employment sub-index fell to an 11-month low of 48.
Analysts had cautioned before Saturday's release that the ongoing Lunar New Year holiday, which began on January 31, probably dragged on factory output in January as manufacturers shut shop for China's biggest annual holiday.
But seasonal factors aside, most analysts noted that China's economy was fighting headwinds that would only grow in coming months as the country hunkers down for sweeping reforms.
A Reuters visit to China's southern manufacturing heartlands in January had showed factories smarting from lacklustre demand. Discouraged, many had packed up earlier than usual for the holidays.
"We expect China's first-quarter economic growth to show a certain degree of a slowdown," ANZ economists Liu Ligang and Zhou Hao said in a note. "China should lower its annual economic growth target to 7 per cent."
The official PMI echoes a separate private survey published by HSBC this month that also showed factory growth in the world's second-biggest economy retreated to a six-month trough in January.
It is widely understood among investors that the days of stellar, double-digit economic growth in China are over as it tries to embrace slower but better-quality growth to protect its environment and cut reliance on investment.
But any signs of moderating growth in China still jolt financial markets as some investors struggle to adjust expectations, while others worry Beijing may mismanage a slowdown and allow growth to fall off more sharply instead.
China's economy narrowly missed expectations for growth to hit a 14-year low last year by expanding 7.7 per cent, just a notch above the government's 7.5 per cent target.
Most analysts polled by Reuters in January believed China can sustain its 2014 economic growth broadly in line with last year's 7.5 per cent target.
Despite investors' jitters, Chinese experts are confident Beijing will raise government spending to support the economy if it looks like it is on the verge of a slump.
They say a stable economy that holds down the jobless rate is the most important precursor to China's ambitious reforms, a factor some mentioned on Saturday.
"Since the PMI stayed above the 50-point level, it shows the basic trend of stable economic growth will not change," said Zhang Liqun, an economist at the Development Research Centre, which helps compile the PMI.
Copyright: Thomson Reuters 2014