Two villagers share food in Nan’s Viengsa district. The province has been hard hit by floods leaving hundreds of people homeless and many others having to spend the night up trees.

In the past three days, 3,545 villagers had suffered slight injuries while moving their belongings away from floods and received medical attention, Pinij said. Among them were 45 cases of broken arms, 50 of diabetes and high-blood pressure and two cases of asthma.

Ten more medical teams from Phayao, Chiang Rai, Uttaradit, Phrae, Lampang and Chiang Mai along with medical supplies would assist doctors and nurses at Nan Hospital to treat 300 patients.

Nearly 70 mobile medical teams were also sent to marooned villages, Pinij said, adding that the worst hit area was Tha Wang Pha district, which was only accessible by flat-bottom boats.

Permanent Secretary for Public Health Dr Prat Boonyawongvirot said overall the flood situation in Nan had improved and services at Nan Hospital were operational again.

Nan public health official Dr Pisit Sriprasert, said 80 per cent of Nan residents had sustained scratches while six per cent suffered muscle strains from moving their belongings to higher ground. The rest had foot and skin diseases.

The most worrying issue was clean drinking water, and he urged villagers to drink from sealed bottles certified by the Food and Drug Administration, and not to bathe or wash their faces in the reddish floodwater as it may be contaminated.

Meanwhile, floodwater from upper Muang and Tha Wang Pha districts had caused the Nan River to burst its banks inundating nearly 3,000 houses in five tambons of Wiang Sa district and leaving it under two-metres of water since Monday night.

All roads linking residents to other areas had been cut.

Wiang Sa district Chief Wichit Boonkangwan said he had initially dispatched 10 flat-bottom boats to deliver food and drinking water to the affected villagers and evacuate some people to safer places. He said the damage should be less, as villagers were warned beforehand and the district had prepared for the disaster.

The Third Army Region also landed helicopters at the district office in case emergency patients needed airlifting - and to carry food and supplies to inaccessible areas, a local reporter said.

The floodwaters would pass through the Na Noi and Na Mun districts' non-residential areas before it poured into the Sirikit Dam in about two days time.

Meanwhile, Irrigation Department chief Samart Chokekhanaphithak said the slow flow and drainage of floodwaters was caused mainly by poor underground drainage on roads, bridges and railway bridges. It would require around Bt4.15 billion to build more drains or improve the existing ones.

Some 402 locations needed immediate improvement, he said, adding that he and officials from the Highways Department and the State Railway of Thailand would discuss the problem on August 30, at a meeting chaired by caretaker deputy prime minister and industry minister Suriya Jungrungreangkit.