Bangkok: Bangkok braced for rising waters encroaching on the fortified city on Sunday as the death toll from two weeks of nationwide flooding rose to 38, emergency officials said.

The floods, which began on October 10, have affected millions of people across huge swathes of the country, inundating thousands of homes and leaving authorities struggling to reach people stranded in remote areas.

The capital has reinforced its flood walls with 200,000 sandbags and will build temporary wooden bridges in 27 communities to help people cross over waterlogged streets.

More than 1,000 water pumps are on standby and authorities are preparing schools, monasteries and mosques in 13 districts for evacuation.

Prime Minister Abhisit Vejjajiva said that while floods in the kingdom's east and northeast were declining, the situation in central provinces was concerning, especially with high tides expected in the next few days.

"I'm trying my best to mobilise all possible assistance to solve this problem," he said on his weekly television broadcast.

The Emergency Medical Institute of Thailand reported a further six deaths to add to Saturday's toll of 32, who were swept to their deaths or killed in accidents as vehicles were carried away by the churning waters.

The two worst-hit northeastern provinces of Nakhon Ratchasima and Buriram have each reported six deaths, while six people were also killed in Lop Buri and three died in Khon Kaen.

A further 17 people have died in eight more provinces across central, northeastern and eastern areas, including one in Nonthaburi province, just north of Bangkok.

The Irrigation Department on Saturday issued warnings to people living in seven low-lying provinces, including Bangkok, as water from further north began to flow downstream.

Around 4,000 cubic metres of water per second was expected to flow into the capital's Chao Phraya river, which coupled with high sea levels surging from the other direction could cause floods in parts of the city.

More than 2.5 million people, or 828,443 households, have been affected by the two weeks of flooding, which has hit 30 out of Thailand's 76 provinces, the Department of Disaster Prevention and Mitigation said.

Bad weather has battered countries in the region in recent weeks, with dozens killed in Vietnamese floods and nearly 50 people left dead in the Philippines and Taiwan by Typhoon Megi, which has roared into southern China.

In western Myanmar, Cyclone Giri killed at least one person on Friday and left tens of thousands in need of help.