The Hong Kong police fired live rounds of ammo at protesters, critically injuring one, as the Chinese-ruled territory spiralled into rare working-hours violence in its 24th straight week of pro-democracy unrest.
Hong Kong's Hang Seng shed 2.6% to mark its biggest single-day drop in more than three-months while Chinese stocks also declined, with the Shanghai index falling the most in over four months.
The collapse in Hong Kong's main index "as protests there dangerously escalate, is the culprit behind Asia's sell-off", Jeffrey Halley, senior market analyst, Asia Pacific at OANDA said in a note.
"It is a reflection of the increased fears of direct mainland intervention in the territory. That fear will hang over regional markets this morning, although its effect may be limited time-wise," he added.
Leading losses in the region, the Thai benchmark shed 1%, weighed by financial and consumer stocks.
Siam Commercial Bank fell 2.5% while chemical developer Indorama Ventures PCL dropped 3.8% after posting a slump in quarterly profit.
Also damaging the overall sentiment was U.S. President Donald Trump's remark on Friday that he had not agreed to rolling back the U.S. tariffs sought by China, which contradicted earlier reports of officials confirming the arrangement.
Singapore's main index tumbled as much as 1.1% to mark its worst session in over a month amid broad-based losses.
Tech stocks faltered following Venture Corp's results last Friday, which were not very encouraging, while financials came under pressure after Southeast Asia's top lender DBS Group Holdings flagged a weaker 2020, said Nicholas Yon, equity research analyst at Lim & Tan Securities.
Local property developers exposed to the Hong Kong region such as Hongkong Land Holdings and Jardine Strategic Holdings also traded lower.
Indonesian shares followed suit, as coal miner Bayan Resources dived 19.4% and poultry feed producer Charoen Pokphand Indonesia Tbk PT lost 4.3% to dominate losses on the benchmark.
The Philippine index closed at a near two-week low.
Malaysian shares dipped after data showed September's industrial production rose 1.7% from a year earlier but came in slower than August as manufacturing and mining output declined.
For Asian Companies click;
SOUTHEAST ASIAN STOCK MARKETS
Change on the day
Market Current Previous close Pct Move
Singapore 3240.65 3264.3 -0.72
Bangkok 1622.12 1637.85 -0.96
Manila 8009.38 8065.76 -0.70
Jakarta 6148.74 6177.986 -0.47
Kuala Lumpur 1608.15 1609.73 -0.10
Ho Chi Minh 1016.75 1022.49 -0.56
Change so far in 2019
Market Current End 2018 Pct Move
Singapore 3240.65 3068.76 5.60
Bangkok 1622.12 1563.88 3.72
Manila 8009.38 7,466.02 7.28
Jakarta 6148.74 6,194.50 -0.74
Kuala Lumpur 1608.15 1690.58 -4.88
Ho Chi Minh 1016.75 892.54 13.92
(Reporting by Anushka Trivedi in Bengaluru; Editing by Rashmi Aich)
By Anushka Trivedi
Stocks treated in this article : Hang Seng
, Venture Corporation Limited
, DBS Group Holdings Ltd
, Siam Commercial Bank PCL
, Hongkong Land Holdings Limited
, Jardine Strategic Holdings Limited
, Bayan Resources Tbk PT
, Indorama Ventures PCL
, Charoen Pokphand Indonesia Tbk PT
, Remark Holdings, Inc.