Shares in Hong Kong and Shanghai have tumbled after data from China showed manufacturing activity contracted for an 11th straight month in September.
Hong Kong's benchmark Hang Seng Index on Thursday dropped 1.20 per cent, or 250.99 points, to 20,590.92 on turnover of HK$52.67 billion ($A6.51 billion).
British banking giant HSBC said the preliminary reading of its China Purchasing Managers' Index (PMI) for September was 47.8, which is slightly up on August but still below 50, pointing to shrinkage.
The data add to long-running worries about the world's No.2 economy, which has seen its key export sector pummelled by shrinking demand in the crucial European and US markets.
Mobile-phone operator China Unicom slumped 5.2 per cent to $HK12.46, while offshore oil producer Cnooc retreated 3.5 per cent to $HK15.64.
Goldminers Zhaojin Mining shed 1.9 per cent to $HK13.38 and Zijin Mining dropped 3.8 per cent to $HK3.07.
Chinese shares closed down 2.08 per cent at a 43-month low. The benchmark Shanghai Composite Index lost 42.99 points to 2,024.84 on turnover of 54.0 billion yuan ($A8.24 billion). The close was the lowest since February 2, 2009.
"While economic growth continues to slow, we haven't seen further stimulus measures from the government. The market will keep consolidating with a downward bias," Orient Securities analyst Cheng Gang told Dow Jones Newswires.
Among resources stocks Chengtun Mining slumped 6.97 per cent to 11.34 yuan, Shanxi Coking Coal lost 6.81 per cent to 8.07 yuan and PetroChina shed 1.71 per cent to 8.63 yuan.
Technology firms fell on profit-taking. CEC CoreCast, which makes communications products, dropped 5.20 per cent to 5.84 yuan and Datang Telecom Technology fell 5.15 per cent to 9.03 yuan.