Thai officials say they can no longer hold back the floodwaters that are bearing down on the capital.

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.

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.

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.