Thailand's prime minister has urged Bangkok residents to get ready to move their belongings to higher ground as the country's worst floods in half a century begin seeping into the capital's outer districts.
The government has opened several key floodgates in a risky move to let built-up water flow through the canals toward the sea. It is not known how much the canals will overflow.
Reporters saw water entering homes in Bangkok's northern Lak Si district, along the capital's main Prapa canal. The water rose to knee-level in some places but damage so far is minor and not affecting Bangkok's main business district.
Prime minister Yingluck Shinawatra told reporters the Prapa canal was a big concern. "I would like to ask people in all districts of Bangkok to get ready to move their belongings to higher ground as a precaution," Ms Yingluck said, while also urging people not to panic.
Ms Yingluck invoked her powers under the Disaster Prevention and Mitigation Act giving her overriding authority over all other official bodies, including local governments, to fight the crisis.
The action should allow better co-ordination with the municipal authorities in Bangkok, who normally have legal authority to make their own decisions. It also helps project Ms Yingluck as a take-charge leader, after weeks of seeming indecision and confusion.
Bangkok Governor Sukhumbhand Paribatra said managing the Prapa canal was a "top priority" but vast pools of runoff draining through it from the north are expected to intensify.
The immense networks of sandbagged barriers could deteriorate under pressure from the water, since they were not designed as dams.
Thailand's government said at least 342 deaths occurred there, mostly from drowning as floodwaters crept across the nation since July. The floods have submerged land in about a third of the country, leaving some towns under more than 6ft of water.
Economic analysts say the floods have cut Thailand's 2011 GDP projections by as much as 2%. The latest damage estimate of 6 billion US dollars (£3.8 billion) could double if floods swamp Bangkok.