BANGKOK (AP) — Thailand’s catastrophic floods may take up to six weeks to recede, the prime minister said Saturday, as the human toll from the crisis rose to 356 dead and more than 110,000 displaced.

Excessive monsoon rains have drowned a third of the Southeast Asian nation since late July, causing billions of dollars in damage and putting nearly 700,000 people temporarily out of work.

Colossal pools of runoff from the north have been bearing down on the capital for the last two weeks. In recent days, water has submerged districts just outside Bangkok’s northern boundaries, while on Friday, floodwaters began spilling over canals within the city’s outermost districts, causing damage to homes.

Some flooding on Bangkok’s outskirts was expected after Prime Minister Yingluck Shinawatra ordered floodgates opened in a risky move to drain the dangerous runoff through urban canals and into the sea. So far, most of the metropolis of 9 million people has escaped unharmed, and its two airports are operating normally.

In a weekly radio address Saturday, Yingluck said that “during the next four to six weeks, the water will recede.”

In the meantime, the government will step up aid to those whose lives have been disrupted, including 113,000 people Yingluck said were living in temporary shelters after being forced to abandon submerged homes.

The government said at least 356 people have died in the floods since July.

The floods are the worst to hit the country since 1942, and the crisis is proving a major test for Yingluck’s nascent government, which took power in July after heated elections and is coming under fire for not acting quickly or decisively enough to prevent major towns north of the capital from being ravaged by floodwaters.

Thai Buddhist monks carry sandbags to fortify their barriers from rising floodwaters at the Weeru Wanaram temple at Don Muang District, in Bangkok, Thailand, Saturday, Oct. 22, 2011. Pic:AP

The Labor Ministry says the flooding has put nearly 700,000 people temporarily out of work, many of them from five major industrial estates north of Bangkok that were forced to suspend operations. Among those affected are Japanese carmakers Toyota and Honda, which have halted major assembly operations. The electronics industry has also suffered, including computer hard drive maker Western Digital, which has two major production facilities in the flooded zone.

In an interview published in the Bangkok Post, Science and Technology Minister Plodprasop Suraswadi said natural and manmade factors combined to create the crisis.

Seasonal monsoons came six weeks early and have lasted longer than usual, filling reservoirs, dams, and fields with 30 percent more rainfall than average. At the same time, the government kept too much water in dams over the summer in a bid to save water for rice cultivation, Plodprasop said.

Overall, about 700 billion cubic feet (20 billion cubic meters) of rainfall has drenched Thailand over the last several months, Plodprasop said.

About half of that has already drained into the sea, leaving about 350 billion cubic feet (10 billion cubic meters) of water threatening Bangkok, much of it spread across rice fields in Thailand’s central plains.

Plodprasop said it will take about 20 more days to drain those floodwaters into the Gulf of Thailand, a task he said was complicated by the fact that the nation’s irrigation system was designed to control water flows for farming and consumption — not to prevent floods.

“We have never faced such a huge mass of floodwater in the fields,” Plodprasop said.

He said he believed inner Bangkok “should be safe, as we have an extensive drainage system with water pumps to drain excess water out quickly.” But some of the city’s outskirts could flood up to 6 feet (2 meters) deep, he said.

While Bangkok has so far survived mostly unscathed, images of disaster just outside the city have spooked residents, who are girding for the worst after Yingluck urged all Bangkokians to move valuables to higher ground.

Thousands of cars are parked on elevated highways as drivers try to safeguard their vehicles. And some supply lines are being affected: one Thai company that delivers drinking water to city residents and businesses sent out an SMS to customers announcing its services had been halted because of the crisis.

“The flooding this time is a critical problem,” Yingluck said. “We need cooperation and sacrifice from everyone.”

To fight the crisis, Yingluck on Friday invoked her powers under a disaster law that gives her authority over all other official bodies, including local governments. The move should allow better coordination with the municipal authorities in Bangkok and help project Yingluck as a take-charge leader, after weeks of seeming indecision and confusion.