Thai authorities warned flood victims Wednesday of an increased danger of electrocution in densely populated Bangkok and its suburbs as the toll from the worst inundation in decades surged above 400.

While the centre of the capital Bangkok remains dry, residential areas in its outskirts and to the north have been submerged in water up to people's waists or even deeper as runoff creeps south from the central plains.

The government said the disaster has now killed 427 people -- an increase of 42 from the figure reported a day earlier. While drowning was the most common cause of death, dozens have also been electrocuted.

"In the past 10 days deaths from electrocution rose from just nine to 36 and about 80 percent of those were in the provinces surrounding Bangkok," said a senior public health ministry official, Porntep Siriwanarangsun.

"I'm sure many cases are not reported. If this issue is not addressed it will be a major cause of death," he told AFP.

Most instances of fatal electrocution occurred when people returned to their flooded one-storey homes, unaware of the risk.

"In many cases victims died because of senseless action," Porntep said.

So far none of the deaths in the official toll were in Bangkok, where the risk of drowning is considered relatively low because the water is fairly shallow in most areas and the current is not strong.

A bigger worry is children swimming in contaminated water, Porntep said, adding that the authorities would need to clean up garbage soon after the floods recede to prevent leptospirosis, a severe bacterial infection.

The country will have to deal with 1.45 million tonnes of uncollected rubbish after the floods end, according to the environment ministry.

Despite fears about hundreds of crocodiles that have escaped from farms, there have been no reports of attacks.

"There is no evidence that crocodiles on the loose attacked any flood victims," said agriculture ministry official Somwang Phimonbut, who added that eight of the animals had been caught alive.

The floods, triggered by unusually heavy monsoon rains that began three months ago, have damaged the homes and livelihoods of millions of people across the kingdom.

Residents in affected areas have complained that their homes are being sacrificed to save central parts of the sprawling metropolis, home to 12 million people, leading to protests and the destruction of some dykes.

The cabinet on Tuesday approved compensation of up to 30,000 baht (just under $1,000) for each home that has been damaged or destroyed.

Prime Minister Yingluck Shinawatra expressed concern about situation in the western part of Bangkok.

"This area will be slower to return to normal than others," she told reporters, asking for the public's support in a crisis that she said was not her fault.

"All the dams were full when I assumed office and five storms came afterwards," she said, adding that the government would try to speed up the drainage of floodwater to the sea.

Yingluck has refused calls from the opposition to declare a state of emergency that would give greater powers to the military to deal with unrest.

Army chief Prayut Chan-o-Cha also said that there was no need to invoke emergency rule to deal with dissatisfied flood victims.

"To use the special law will cause confrontation between people and soldiers," he told reporters.

The financial cost of the floods is estimated at 180 billion baht ($5.8 billion), according to the finance ministry, which said 2011 economic growth would be cut by 1.7 percentage points but still exceed 2.0 percent.