Thailand on Tuesday declared a three-day holiday in Bangkok and other flood-affected areas as high tides are forecast to flow up the city's main river and worsen floods creeping into the city.

Schools, businesses and government offices will shut on Thursday and Friday, and the following Monday, creating a five-day break in the capital and 20 other provinces.

"The cabinet today approved the declaration of October 27 through to 31 as holidays," Pracha Promnog, head of the Flood Relief Operations Centre (FROC), said after ministers met to discuss the escalating crisis in Bangkok.

The central bank said it was still being decided whether to shut down financial markets as well.

The announcement came after Bangkok governor Sukhumbhand Paribatra made a televised address warning residents along the Chao Phraya river to be on "full alert" after it reached record highs of 2.30 meters on Monday.

"If the situation continues in these circumstances, the water level this weekend will hit 2.60 meters, while our average flood embankment is 2.50 meters high," he said.

Prime Minister Yingluck Shinawatra's cabinet met north of the city centre at Don Mueang airport, which is doubling up as a shelter and a headquarters for the relief operation, but is already surrounded by water-logged roads.

"We are concerned about evacuees because there is a problem with travelling here," Yingluck said ahead of the meeting.

"We will move them to safe areas," she said, but added that for now FROC's operations would remain at the airport.

The floodwaters are creeping further into the city of 12 million people after three months of heavy rains that have plagued other parts of the country, killing more than 360 people and damaging millions of homes and livelihoods. (AFP)