Angry residents in flooded Bangkok protested on Monday, briefly blocking a major highway as frustration mounted that parts of the Thai capital are suffering badly while the centre stays dry.

Thailand's worst floods in half a century, triggered by months of unusually heavy monsoon rains, have left at least 562 people dead around the kingdom and damaged millions of homes and livelihoods.

After weeks of flooding, waters in some Bangkok districts have receded significantly. An AFP photographer said the water level in the Lat Phrao and Mo Chit areas, on the northern edge of the city centre, had fallen by nearly a metre (three feet) in 48 hours and inhabitants were no longer using boats to get around.

But elsewhere anger is growing that residential areas are being sacrificed to preserve Bangkok's commercial and tourist heart.

In the west of the city, around 200 people blocked a section of the Rama II road, the main route linking the capital to southern Thailand, to demand extra water pumps to help drain their swamped neighbourhoods.

"The villagers were not happy that there were not enough pumps to drain the floods," local police chief Colonel Nakarin Sukontawit said.

"The BMA (Bangkok Metropolitan Administration) agreed to bring two more pumps today, so the villagers decided to stop their protest."

Around 70 people also gathered at a major floodwall in northern Don Mueang district, watched by about 30 police officers, to stop the authorities repairing a gap they had opened to allow water to drain away from badly flooded areas.

A spokesman for the Flood Relief Operations Centre (FROC), the government agency charged with dealing with the floods, said a compromise had been struck to partially repair the eight-metre (26-foot) breach.

"A meeting today between FROC and the BMA agreed that to ease residents' problems, a half-height dike will be put up in one half of the opening and the other half will be left clear," Police General Pongsapat Pongcharoen told AFP.

People in the area -- many of whom have been living in waters waist-deep or worse for almost a month -- had threatened to step up their protest if the opening was repaired.

The 15-kilometre (nine-mile) floodwall, mostly made up of huge sandbags weighing up to 2.5 tonnes, is a key defence preventing run-off waters from the north from swamping Bangkok's glitzy downtown area.

"The water in my house reaches as high as my neck," said 65-year-old Wattana Klongsakon, adding that she was "satisfied" to see the brown liquid rushing through to the other side of the damaged barrier.

"If they rebuild it, we will definitely block the toll road", she said, referring to a major nearby route linking Bangkok to the north.

In an effort to spare Bangkok's economic and political heartland, authorities have been trying to drain the floods through waterways in the east and west of the sprawling capital and out to sea.

Japanese motor giants Honda and Nissan said they had resumed partial production in Thailand on Monday, after work was suspended due to parts shortages caused by the floods.

Under-pressure Prime Minister Yingluck Shinawatra, facing the first serious test of her fledgling premiership, pleaded for patience and unity on her Facebook page on Monday.

"People suffering in the floods please be patient, please be united as we walk through this crisis," she wrote.

"The government will try to speed up solving the problems as best as we can."

The premier, who only came to power three months ago and has faced criticism of her handling of the disaster, said water levels had started to recede in many areas of the city of 12 million people.

But western districts remained badly affected. The floods have also swamped Bangkok's number two airport Don Mueang, which mostly serves domestic destinations, forcing its closure in late October.

The kingdom's main air gateway Suvarnabhumi, east of the city centre, is operating as normal.