Hong Kong's Hang Seng index plunged 2.5 per cent to 23,393.01 points after police used pepper spray and clubs against protesters demanding democratic reforms in the semi autonomous Chinese territory.
China's Shanghai Composite Index shed 0.1 per cent to 2,680.16 and Tokyo's Nikkei 225 added 0.7 to 17,590.10.
Seoul's Kospi declined 0.8 per cent to 1,965.22. India's Sensex was flat at 28,688.49. Singapore and Sydney also declined, while Manila, Jakarta and New Zealand gained.
Police charged protesters who tried to march to Hong Kong leader Leung Chun-ying's office after organisers said they would step up their campaign for democratic reforms.
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A survey by HSBC Corp. Showed manufacturing activity weakened in November, adding to signs an economic slowdown is deepening. HSBC said its purchasing managers' index declined to 50.0 from the previous month's 50.4 on a 100-point scale on which numbers below 50 show activity contracting.
The bank said domestic demand was sluggish and new orders were weak. China's economic growth slowed to a five-year low of 7.3 per cent in the latest quarter.
Oil prices fell further following last week's decision by members of the Organisation of Petroleum Exporting Countries to maintain production levels despite weaker global demand.
The US benchmark fell more than 10 per cent on Friday to below USD 70 per barrel for the first time since 2010 and is off 35 per cent from its June high. That has battered energy shares but cheaper energy is a boost to import-dependent economies in Asia and elsewhere.