BANGKOK (AFP) - Thais enduring the nation's worst floods in decades have faced marauding crocodiles and threat of snake bites and electrocution, but health experts say the top risks are drowning and disease.

Three months into a crisis that has ravaged the kingdom and is now encroaching on the capital Bangkok, conditions are ripe for a humanitarian disaster and aid agencies are racing to heighten awareness.

"You don't want to create mass panic," said Matthew Cochrane of the International Federation of Red Cross and Red Crescent Societies. "You need to find a balance between being alert and alarmed."

Inundated communities have been warned to watch out for poisonous snakes swimming in the murky floodwaters, as well as electrocution from submerged power points and dangling electricity cables.

Images of crocodiles being captured on Bangkok's outskirts, after escaping from flooded farms where they are bred commercially, have further rattled nerves.

Unusually heavy monsoon rains have swamped much of Thailand, killing more than 370 people and forcing vast numbers to seek refuge in shelters. The waters are now closing in on Bangkok's city centre where they could remain for weeks.

Experts say the priority is to maintain hygiene levels and aid agencies are trying to provide clean water and bathroom facilities -- including floating and collapsible latrines -- to tens of thousands of affected families.

"We're talking about basic sanitation: drinking water that's clean, washing your hands and making sure that areas where you wash and where you defecate are separated," Cochrane said.

"The general concern in any floods is water-borne diseases and mosquito-borne diseases," he added, warning there was often "an increased risk of malaria and dengue fever" in waterlogged areas.

Given the right precautions, a serious outbreak of flood-related disease is not inevitable, he said.

In a country where many cannot swim, the number one cause of death during the disaster has not been disease, but drowning, said Maureen Birmingham, the World Health Organisation's representative in Thailand.

"That's very concerning," she said. "One of the risk behaviours reported is fishing, so we urge people to take care with that."

Cochrane said Thais were generally well-educated on hygiene, which bodes well for epidemic prevention, but a recurring complaint among those affected is a lack of toilet facilities, especially in deeply submerged regions.

"The water came up to the toilet in my house," said Kusuma Glomjai, 34, who lives in a badly hit area of Pathum Thani province, just north of the capital.

"I can't use my toilet so I have to go to a relative's house across the road."

Others in her situation have resorted to defecating in plastic bags, while many other flood victims have voiced concern over the filthy water they are forced to wade through.

"I have no choice. But when I get home, I wash myself," said Surapol Pinpol, 57, as he stood in chest-deep brown water in Pathum Thani.

Birmingham said communicable diseases such as conjunctivitis could spread easily among evacuees, as well as fungal infections of the skin and leptospirosis, a bacterial infection spread through contaminated water.

Cases of skin infections, especially athlete's foot, already number in the thousands, according to Thai health ministry which has deployed mobile medical teams to flood-stricken areas that have treated over half a million people.

Birmingham said hygiene kits, water and sanitation facilities were a top priority but admitted it was "very challenging" to deliver them to all of those of need.

With millions of homes and livelihoods damaged across the country, the impact on mental health is increasingly as worrying as physical damage.

The government said it has set up special mental health units across various provinces and dispatched teams of psychiatrists and psychologists to help almost 100,000 people thought to be suffering from flood-related stress.