The department warned diversion could increase water levels by as much as one metre.

The most significant rise will be at Nonthaburi's Bang Bua Thong district.

Director-general Samart Chokanapitak reported the department was monitoring the approaching tropical cyclone. Cimaron, which hit the northern Philippines yesterday, killing 13 people.

The Meteorological Department reported yesterday that Cimaron was moving west at 15kph and packing winds of 150kph. It is expected to reach Vietnam by the end of the week.

It was expected to bring rain to East and Northeast Thailand but spare the North and heavily-flooded Central regions.

Meanwhile, the irrigation department has diverted huge volumes of floodwater from Thung Phraya Banleau to lower-lying Thung Phra Pimol on the west bank of the Chao Phya between Nonthaburi and Pathum Thani.

Water-course levels in Ayutthaya, Pathum Thani, Nonthaburi, and Nakhon Pathom were expected to rise by as much as one metre as a result.

Director-general Samart warned residents to ensure flood barriers were strengthened.

Nonthaburi and Pathum Thani were swamped on Saturday after 2,000 Ayutthaya locals destroyed flood barriers.

Samart reported that the water volume in the Chao Phya at Nakhon Sawan was 3,517 cubic metres per second (cms) - 175cms down from a day earlier. In the Chao Phya Dam at Chai Nat the rate was 3,450 cms. Flow from Bang Sai in Ayutthaya into Bangkok was running at 3,115 cms.

In the capital, Governor Apirak Kosayodhin said water diversion was underway in preparation for high tides in the Gulf of Thailand between November 6 and November 10 and rains from Cimaron.

The Public Health Ministry was seeking donations for ablution barges that were desperately needed in Sing Buri, Angthong, Ayutthaya, Suphan Buri and Nonthaburi. The barges collect and dispose of human waste before it can contaminate waterways and spread disease. Donations can be made by telephoning 02-590-4347 or 02-590-4353.

The number of patients treated for flood-related ailments had hit 600,000 and the death toll has reached 164. Public Health Ministry spokesman Supan Srithamma said it would have to spend Bt157 million to repair flood-damaged hospitals.

Meanwhile, the Disaster Prevention and Mitigation Department said more than 3.6 million people had been affected by flooding since late August. Overall, 47 provinces were affected by floods and 15 were still suffering.

Some three million rai of farmland had been destroyed and initial estimates of damage were approaching Bt377 million.