Thailand floods: Bangkok braced as drainage begins
More districts in the north of the Thai capital have been told to brace for flooding as water begins to drain through the city's canals to the sea.
On Thursday the government opened several floodgates due to a build-up of water to the north of Bangkok.
It urged residents to move their belongings to higher floors but cautioned against panic.
Thailand is facing its worst floods in decades with more than 340 people dead and a third of all provinces inundated.
Three months of heavy monsoon rain have left swathes of the country flooded. Northern and central areas were worst hit initially but now the run-off is draining south to the sea, threatening Bangkok.
The capital is protected by floodgates, and barriers in key areas have been reinforced with sandbags.
But with suburbs to the north of the city now under water, the government was forced to open some of the floodgates on Thursday.
The authorities want to drain the water to the east and west of the city, avoiding the central hub.
The BBC's Rachel Harvey, in Bangkok, says the move is a change of tactic for the government - and no-one seems entirely sure whether the volume of water can be safely controlled.
"I ask all Bangkok residents to move your belongings to higher ground as a precaution, but they should not panic. It's preparation," Prime Minister Yingluck Shinawatra said.
"We will rapidly assess the situation and regularly inform the public."
Reports said water had flooded homes in the Lak Si district, along a key canal in the north of the city.
Our correspondent says that there is growing concern in the capital after confused, sometimes contradictory, messages from the authorities.
Some shops have reported a flurry of panic buying, while bridges and flyovers have been blocked with parked cars.
The flooding has already taken a toll on the economy, with several industrial parks to the north of Bangkok under water. About 1,000 factories have had to close.
On Thursday, the central bank said the damage to industry amounted to over 100bn baht ($3.3bn; £2.1bn).
Analysts have warned that growth this year could be up to two percentage points less than the 4.1% forecast if Bangkok is flooded.
The tourism industry has so far been largely unaffected, with southern islands escaping the flooding. The main international airport is operating as normal and its flood defences have been fortified.