Prime Minister Yingluck Shinawatra, who is facing her first crisis since taking office in August, said Thursday she has ordered officials to open Bangkok's floodgates and let water pour through the city's canals to the sea.
Officials say they are unsure whether water will overflow the canals into city streets, repeating the scenes of devastation already playing out in suburbs north of the capital.
VOA's Daniel Schearf reports from Thailand
The flooding has forced Japanese automakers with plants in Thailand to curtail manufacturing, slashing output by about 6,000 units a day.
Other industries have also been affected. Japanese electronics giant Sony says it will postpone the global launch of its latest digital single-lens reflex cameras because of the floods. The launch was scheduled for November 11.
The decision to open the floodgates in Bangkok has sparked a new rush to stock up on groceries and supplies, prompting officials to issue a warning against hoarding. Residents have also been ordered to remove vehicles from bridges and expressways.
On the northern edge of the city, water is already filling the streets as the flood surge from central Thailand strains against reinforced barriers. Several industrial estates have already been deluged, with the worst now expected in the next few days.
Downtown shopkeepers such as Saowaluk Chaicharoenwattana are protecting their buildings with sandbags.
"Some days, the government say that it will not flood around this area because it's the center of business, but I thought to protect (my store) first just to be sure," said Chaicharoenwattana.
Nationwide, the death toll after the worst floods in 50 years has risen to 320, with 9 million people affected. The floods have also affected Vietnam, Cambodia and Laos, killing hundreds of people in those countries.
Related report by Daniel Schearf:
Some information for this report was provided by AFP and Reuters.