Thailand's prime minister warned her country that Bangkok, the capital, is facing unprecedented flooding following monsoon rains that have left at least 250 people dead elsewhere in the country.

The flooding, which has severed rail links with the north, shut dozens of highways and swamped ancient Buddhist temples in the city of Ayutthaya, has reached a crisis level, Prime Minister Yingluck Shinawatra said.

Northern areas of the country, including its rice fields, have already been inundated, and the fear is the run-off, combined with high ocean tides and new rain from Tropical Storm Nalgae, will put Bangkok underwater. 

In a radio message Saturday, Yingluck said authorities are hoping to ease the crisis by installing up to 400 water pumps along the Chao Phraya River, which snakes through Bangkok, to help push water to the sea. Seven canals will also be dug on the outskirts of the city, she said.

Government agencies are struggling to cope because "the water volume is extraordinary and is beyond expectations," the prime minister said in a televised address late Friday. "It is now going to have a direct impact on Bangkok." 

Bangkok Gov. Sukhumbhand Paripatra said the situation in the capital — where authorities have piled thousands of sandbags along the banks of rising rivers — is currently under control.  But he said he has ordered city officials to prepare for evacuations. The city government has also been stocking emergency supplies of food and water.

Yingluck visited a pumping station on the outskirts of Bangkok, and said she believes a series of drainage tunnels under the city will be able to handle the floods.

Dams reaching capacity

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Other residents watch as neighbours evacuate their homes in Ayutthaya province, central Thailand, on Saturday. (Sunti Tehpia/Associated Press)

The growing nervousness over the floodwaters worsened with news Sunday of an emergency embankment giving way in the city of Ayutthaya, about 100 kilometres north of Bangkok, sending massive amounts of water into the ancient Thai capital and renowned tourist attraction, Canadian journalist Michael McAuliffe told CBC News from Thailand.

Officials are most concerned about next weekend, which marks the highest tide levels of the month, he added.

"With all this rain that keeps falling, Thailand's dams are reaching capacity," McAuliffe said. "There's concern here that some of them could overflow."

The Department of Disaster Prevention and Mitigation said 253 people have been killed, mostly from drowning, since a series of tropical storms began hitting Thailand at the end of July. It said eight million people in 60 of the country's 77 provinces have been affected by floods and mudslides during that time, and 1.2 million hectares of agricultural land have been damaged.

Earlier this week, Japanese automobile giant Honda Motor Co. suspended production for one week after parts factories were submerged in Ayutthaya, north of Bangkok. At least 43 factories in one of the city's industrial zones have shut down as rising waters damaged equipment and kept nearly 15,000 workers off the job.

The floods are proving a major test for Yingluck's administration, which took office in July. The government has set up an emergency flood relief headquarters at Bangkok's Don Muang airport.

With files from The Associated Press