Floodwaters in Bangkok have reached Don Muang Airport, one of the Thai capital's two main airports and home to the flood relief operation command, which may have to move to another location, according to the governor.

In addition to Don Muang, residents in five other areas should prepare for floods, move their belongings to upper floors and take shelter at evacuation centers, Governor Sukhumbhand Paribatra said in a news conference on Monday.

Thammasat University's gymnasium, which has been used as an evacuation center, is also flooded and without electricity and is itself being evacuated, the governor added.

As a remedy, about 4,000 people will be bused to Rajamangala Stadium in central Bangkok with the help of 300-400 volunteers, according to the governor.

In the east, the industrial estates of Lat Krabang and Bang Chan remained under threat, and volunteers were sought for help with sandbagging.

The governor urged the public not to panic and to follow his reports closely.

In an interview with CNN on Sunday Prime Minister Yingluck Shinawatra said authorities were trying to control the water levels by using all the dams and dikes to cope with an unusually heavy rainy season.

Protecting Bangkok was a priority because it comprises the economic heart of Thailand, she said. "But it doesn't mean we have no concern for the people who are suffering from the flooding," she added.

The decision to divert water through canals in Bangkok means parts of the city and its surrounding suburbs, such as Rangsit, are flooded.

Residents have resorted to moving out of flooded homes by boat or anything that could float - or wading through water with plastic bags of belongings balanced on their heads or pets tucked into clothes.