BANGKOK, Sept 23 — Southeast Asian stock markets fell today as a survey indicating weak factory data from China unnerved investors, with Singapore's key index hitting multi-week lows while large-caps in Indonesia and Thailand faced foreign selling pressure.

Singapore's Straits Times Index was down 1.23 per cent at 2,833.31, the lowest since Sept. 8.

Shares of DBS Group Holdings and United Overseas Bank shed more than one per cent each, and were among the most actively-traded shares.

Confirmation of China's weak PMI numbers will be a drag on sentiment, said broker NRA Capital.

“Though the number was not unexpected, the confirmation brings with it continued uncertainty to global markets which have already been hit by negative news all over,” broker NRA Capital said in a report.

Activity in China's factory sector shrank at a faster pace than expected in September as domestic and export demand continued to slump, a private survey showed.

Asian stocks fell today as fears of an entrenched global economic slowdown gripped investors.

Stock markets in Singapore, Malaysia and Indonesia will all be closed tomorrow for a public holiday.

Kuala Lumpur's composite index hit a more-than-one-week low while Jakarta hovered at its lowest in four weeks, with foreign selling sending Bank Rakyat Indonesia 4.3 per cent lower.

In Bangkok, shares of the country's biggest conglomerate Siam Cement fell almost three per cent to a level last hit on Aug. 31. The broader SET index was down 0.7 per cent at its lowest since Sept 8.

“The selling will probably be related to portfolio adjustment of foreign investors which hit large-caps in the region as well,” said Pichai Lertsupongkij, a senior analyst at broker Thanachart Securities.

Vietnam's benchmark VN Index dipped 0.38 per cent by midday today, with banking and energy stocks leading the fall while the market lacked supporting news. — Reuters