BANGKOK (Reuters) - Thai rescue workers scrambled on Monday to prevent a humanitarian disaster as the worst flooding in half a century swamped large sections of the country, shut factories and stranded thousands of people.
Nearly 270 people have been killed in heavy monsoon rains, floods and mudslides since July that have battered 30 of Thailand's 77 provinces, authorities said.
About 3.4 million acres (1.38 million hectares) of farm land is under water -- about 13 times the size of Hong Kong. More then 700,000 homes have been destroyed or damaged.
In the hard-hit central province of Ayutthaya, 198 factories in a big industrial estate, including an assembly plant of Honda Motor Co Ltd, closed after flood waters breached a wall of sandbags at the weekend.
"There will certainly be some impact on production due to the flooding in Ayutthaya," Ammar Master, a senior market analyst at the Asian unit of J.D. Power and Associates, a California-based industry research firm.
"While automakers will have components in stock, we expect a slowdown in production in the immediate term," he said. "Measures taken are likely to be similar to those implemented in the immediate aftermath of the (March earthquake) disaster in Japan."
Industry Minister Wannarat Channukul estimated the initial cost of damage had reached more than 20 billion baht ($645 million)in Ayutthaya province alone.
"This is just a rough estimate. We still can't get to all parts of the area due to heavy flooding," he said, adding that he would travel with Prime Minister Yingluck Shinawatra to Ayutthaya later on Monday.
Bangkok, much of which is only two meters (78 inches) above sea level, has seen only minor flooding but officials are preparing for worse this week and considering evacuation plans for some sections of the city of about 12 million people.
The Chao Phraya river running through the capital, already high because of water coming from overflowing dams in the north, could be swollen from around October 13 by further heavy rain plus high sea tides affecting its estuary.
First Army Region Commander Lieutenant General Udomdej Sritabutr said three evacuation centers had been set up to support 7,000 evacuees in Ayutthaya province. At least 2,000 rescue workers have been sent to the area with nearly 1,000 boats and 155 trucks.
Ayutthaya provincial hall has been turned into a makeshift evacuation center, packed with thousands in tents.
Economists are cutting forecasts for economic growth this year because of the floods but say reconstruction work will push up demand eventually, especially early next year.
Nearly 200 factories, including one run by Japanese car maker Honda, closed in Ayutthaya because of flooding. The Rojana estate in Ayutthaya, run by Rojana Industrial Park Pcl, was flooded after a wall of sandbags collapsed.
A Honda spokeswoman said it had moved about 3,000 assembled cars from the estate to other areas. Hana Microelectronics Pcl has also had to close its plant in Ayutthaya.
The commerce ministry said on Friday it had slashed its forecast for the main rice crop, which farmers are just starting to bring in, to 21 million tonnes from 25 million because of the flooding.
Thailand is the world's biggest rice exporter. The crop damage will add to the pressure on export prices, already being forced up by the high buying price set under a government intervention scheme aimed at helping poor farmers.
Other Southeast Asian countries have suffered serious flooding in recent weeks because of heavy monsoon rains combined with tropical storms.
The death toll from two strong typhoons that cut across the north of the Philippines' main island and left behind widespread flooding had risen to 101 as of Sunday, the national disaster agency said.
Additional reporting by Ploy Ten Kate, Writing by Alan Raybould. Editing by Jason Szep and Jonathan Thatcher