BANGKOK (AP) -- Thailand's prime minister urged Bangkok's residents to get ready to move their belongings to higher ground Friday as the country's worst floods in half a century began seeping into the capital's outer districts.
The warning came one day after the government opened several key floodgates in a risky bid to let built-up water flow through the city's canals toward the sea. Authorities had said the canals could overflow, but it was not known to what degree.
An Associated Press Television News team that visited the area on Friday saw water entering homes in Bangkok's northern Lak Si district, which is located along the capital's main Prapa canal. The water had risen to knee-level in some places but damage has so far been minor and not affected Bangkok's main business district.
Prime Minister Yingluck Shinawatra told reporters the Prapa canal was a big concern as water levels running through it had risen significantly overnight.
"I would like to ask people in all districts of Bangkok to get ready to move their belongings to higher ground as a precaution," Yingluck said, while also urging people "not to panic."
Gov. Sukhumbhand Paribatra said managing the Prapa canal was a "top priority" but vast pools of runoff draining through it from the north are expected to intensify.
Authorities have said immense networks of sandbagged barriers could deteriorate under pressure from the water, since they were not designed as dams. Yingluck said Wednesday there were no other options to slow down the approaching water.
Excessive rains and storms have wasted a vast swath of Asia this year, killing 745 people -- a quarter of them children -- in Thailand, Cambodia, Vietnam, Laos and the Philippines, according to the United Nations.
Thailand's government said Friday at least 342 deaths occurred here, mostly from drowning as floodwaters crept across this Southeast Asian nation since July. The floods have submerged land in about one-third of the country, leaving some towns under water more than six-feet-high (two-meters-high).
The threat of floodwaters swamping glitzy downtown Bangkok and ruining treasured ancient palaces and chic boutiques along skyscraper-lined avenues has loomed large over this giant metropolis for weeks.
No major damage has occurred yet, and life is mostly normal in most of the capital. But many Bangkokians are girding for the worst.
"The water is coming, it's inevitable," Oraphin Jungkasemsuk, a 40-year-old employee of Bangkok Bank's headquarters, said Thursday. Its outer wall is protected by a six-foot-high (two-meter-high) wall of sandbags wrapped in thin plastic sheeting.
"They are fighting a massive pool of water. They cannot control it anymore," Oraphin said. "There are barriers, but it can come into the city from any direction, even up through the drains."
Much is at stake. Economic analysts say the floods have already cut Thailand's 2011 GDP projections by as much as 2 percent. Damages could run as high as $6 billion -- an amount that could double if floods swamp Bangkok.
This week, Bangkok's governor called for 1 million sandbags to reinforce vulnerable spots -- on top of 1 million more called for earlier this month. The Thai military and volunteers have been bolstering flood walls that ring Bangkok for miles (kilometers), many of them along a complex network of swamped canals.
Oraphin Milintanon, who works at a camera shop in the capital where customers must step across sandbags to get inside, has watched the floods advance with increasing alarm.
The water first swept through her hometown in the now-heavily submerged city of Ayutthaya, just north of Bangkok. Then it poured through her current home in Nonthaburi province.
Oraphin now lives with a sister in a dry part of Bangkok, but tales of water creeping closer are spooking residents. She said her brother, living elsewhere in Nonthaburi, was recently awaken by the flood water itself -- which welled up suddenly into his home as he slept on his bed.
"It can come very fast ... the problem is, nobody knows from where it will come," Oraphin said Thursday. The only thing certain, she added, "We know it is coming soon."