Traffic clogged roads out of Bangkok Friday as thousands of people fled ahead of a high tide expected to worsen floods that have inundated factories and prompted foreign governments to warn citizens to stay away from one of Asia's biggest cities.

Authorities have expressed concern that Bangkok's main Chao Phraya River will burst its banks over the weekend during the unusually high tide that begins Friday. Buildings across Bangkok have been sand-bagged for protection, and some vulnerable streets were nearly deserted.

Thailand's worst flooding in half a century, caused in part by unusually heavy monsoon rain, has killed 377 people since mid-July and disrupted the lives of nearly 2.2 million, until now mostly in the north and central provinces.

Prime Minister Yingluck Shinawatra said she was considering a proposal to dig channels into some roads in eastern Bangkok to drain water into the Gulf of Thailand, an idea backed by the chairman of the Thailand unit of Toyota Motor Corp whose factories have been badly flooded.

We need to look into several details on whether it works, Yingluck told reporters.

The Meteorological Department warned residents living along the Chao Phraya they could face rising waters. Roads around the Grand Palace, a top tourist attraction, are partially flooded along with some streets in densely populated Chinatown.

Friday morning, on a street in front of the Grand Palace normally bustling with tourists, a two-metre (6 1/2-ft) snake was caught by a motorcycle taxi driver. Residents have also had to contend with crocodiles escaping from flooded farms.

While many of the inner-city streets of Bangkok remained dry, the suburbs continued to struggle with surging waters.

In the riverside shantytown of Bang Phlad, small wooden homes were knee-deep in foul-smelling water with rubbish floating on the surface. Residents carried belongings above their heads, struggling against the current of water pumped back out to the river.

Tem Kaewkeow, 73, sat on a pile of tyres, staring at the blank screen of a half-submerged television set.

Everything is damaged, but what can I do? This is the force of nature, he said, shirtless and sipping on water he had boiled on a small gas stove.

I don't plan to leave. This is my home.

PROTECTING THE HOSPITAL

At the district's Yanhee hospital, two dozen emergency room doctors and nurses shovelled sand into sacks to fortify a one-metre (3-ft) wall protecting the building as water levels rose in a nearby canal brimming with trash.

Everyone here is working around the clock to protect the hospital, said Dr Supot Sumritvvanitcha, the hospital's chief executive. We're using trucks, motorbikes and boats to get help to people. Yesterday, we brought a pregnant woman here by boat to deliver a baby.

Bangkok Governor Sukhumbhand Paribatra told reporters late Thursday that floodwaters might overflow embankments. I'll continue fighting and won't let all of Bangkok be flooded.

Yingluck, a novice politician who only took office in August, has said the crisis had now reached a critical point.

It seems like we're fighting against the forces of nature, massive floodwater that is causing damage to several of our dikes, she said. What we can do now is to manage it, so that it flows slowly, otherwise everybody will suffer.

Yingluck's government declared a five-day holiday from Thursday to allow people to leave. Roads out of the city to the flood-free south were jammed. Many were heading for the seaside town of Hua Hin and the eastern resort city of Pattaya, where hotel rooms and homes to rent were scarce.

Bangkok, a low-lying city of at least 12 million that accounts for 41 percent of Thailand's $319 billion (198 billion pounds) economy, is in danger from run-off water from the north coinciding with the high tide on the Chao Phraya, already at a record high level.

At least seven huge industrial estates have also had to close to the north of Bangkok. The central bank has revised its growth forecast for Southeast Asia's second-biggest economy to 3.1 percent this year from 4 percent as a result. The finance minister's projection is a gloomier 2 percent.

Deputy Prime Minister Kittirat Na-Ranong said Thursday he expected job losses of no more than 10 percent of those employed in the shuttered industrial zones and there would be plenty of work when recovery efforts start.

The government still need hundreds of thousands of workers for reconstruction, Kittirat told reporters.

The defence ministry said 50,000 armed forces personnel were standing by with 1,000 boats and 1,000 vehicles to help evacuate people. Authorities said Sai Mai, a third district in the city's north, was in danger and residents should evacuate.

The government crisis centre said there would soon be evacuation centres in eight provinces that could take in between 100,000 and 200,000 people.

Late Wednesday, the governor warned that dikes might not hold and the city could be swamped. Yingluck has said floodwater could remain in the capital for up to a month.

(Additional reporting by Apornrath Phoonphongphiphat and Damir Sagolj; Editing by Ron Popeski)