Prime Minister Yingluck Shinawatra said on Thursday Thailand was in crisis and the government was struggling to cope as the worst floods in half a century threatened to engulf the capital, Bangkok.
Ms. Yingluck, under fire for her management of the flooding that has killed at least 320 people since July and devastated industrialized provinces in the centre of the country, called for national unity in the face of the crisis.
"I have to admit the government can't keep a close eye on every spot. Now is a time of national crisis. Everybody should work together," she said at a crisis centre set up at Bangkok's Don Muang airport.
"Blaming each other won't help. Today we need unity to solve the problem," she added.
One inner city area was under threat on Thursday after floodwater breached a waterworks canal, officials said.
Shelters for as many as 45,000 people were being prepared as a precaution, as residents of several northern districts packed up their belongings and left or waded waist-deep through normally bustling shopping streets.
The worst flooding in half a century now covers a third of Thailand's provinces, some four million acres in the north, northeast and centre of the country.
Huge industrial estates to the north of Bangkok have been swamped and the central bank put the damage to industry at more than 100 billion baht ($3.3-billion) on Thursday.
Japan's Sony Corp. said on Thursday it would delay the launch of several new cameras due in November after floods forced it to halt production at some Thai plants.
The output of Japanese car makers has fallen by about 6,000 units a day because of the flooding.
Rice traders and industry analysts said as much as 3.5 million tonnes of paddy, equivalent to two million tonnes of milled rice, may have been damaged and loading of 100,000 tonnes may have been delayed because of the flooding.
Thailand is the world's biggest rice exporter.
The damage to the economy will be far higher if flooding hits Bangkok, which accounts for 41 per cent of gross domestic product.
Pracha Promnok, justice minister and head of the government crisis centre, said city officials had been pumping water out overnight in the Samsen and Makkasan areas, which are just north of the royal palace and other prime tourist sites.
"If we can't control the situation or things go wrong with the water pumping machine or we can't pump water in time, then there's a chance that our Bangkok will be swamped," Mr. Pracha told Channel 3 television, adding that the water level in the morning was still manageable.
Water from the north is flowing towards Bangkok and the authorities have been trying desperately to divert it around the inner city using a defensive system of dikes and canals.
The immediate danger seemed to have passed at the weekend, when high estuary tides and heavy rain added to the problem, but residents are braced for trouble again.
In one northern district, floodwater flowed into the canals as villagers tried desperately to repair an embankment with improvised sandbags. Some people waded through waist-high water, others rowed through shopping streets on makeshift rafts.
"I'm really scared, I couldn't sleep last night. I heard the water would come. I didn't know what to do," said Sakor Byuanpanat, 54, in the Sai Mai district, whose home was knee-deep in water.
A survey of 415 residents in Bangkok and nearby provinces by pollsters at Assumption University this week showed 87 per cent thought the government's information was unreliable.
Concern about contaminated tap water prompted Bangkok residents to rush to buy bottled water on Thursday. One central supermarket had sold out.
Some 162 shelters have been prepared in case of evacuation and people in seven districts in the northeast of Bangkok were told to prepare for flooding. About 200 families were evacuated late on Wednesday and people were told to move cars and valuables to higher ground.
Mr. Pracha said the flow of water down from Nava Nakorn, a big industrial estate north of Bangkok that is completely flooded, and elsewhere in Pathum Thani province was strong but the dikes were holding.