Thailand's efforts to completely block floodwaters from reaching the capital Bangkok had been unsuccessful as the strong currents broke through barriers at Pin Klao area in Thon Buri that has been keeping the outpouring of the Chao Phraya River.

Reports gathered said this development, which occurred late Monday, had closed down major roads in Bangkok on the west and east side of the river.

Deputy Bangkok Governor Pornthep Techapaiboon said in a press briefing that about 4,000 million cubic metres of flood water from Ayutthaya will reach Bangkok on Tuesday.

"The problem is City Hall can drain no more than 400 million cu m of water a day," Mr Pornthep said.

The deluge of flood water will enter the west of Bangkok via Nakhon Pathom, Nonthaburi and sweep into Khlong Thawi Watthana, Khlong Bangkok Noi and Khlong Bang Phlad and is expected to reach up to three metres high.

The Bangkok Post said in a related report that water level in the Chao Phraya River reached a record high yesterday, rising to 2.3 metres above sea level against 2.27 metres back in 1995.

Residents living in low-lying areas are advised to evacuate to shelter centers.

Prime Minister Yingluck Shinawatra reiterated that amidst the fast-turn of events, government authorities in-charge are doing their best to update the public of the situation.

"The government has no intention of concealing information. We provide the public with regular updates. But too many new factors keep cropping up," Ms Yingluck said.

Flood waters from the north has reached the north of Bangkok because the Royal Irrigation Department (RID) could not close the Khlong 1 sluice gate in Rangsit as the water flow was too strong and high. The raging torrents could burst through the water gate.

Ms Shinawatra said areas near the Chulalongkorn sluice gate down to Sai Mai district are at risk of floods despite efforts to divert waterflow to the east of Bangkok.

She said there was concern for low-lying areas in the south of Bangkok and in Thon Buri. She added that hopefully the diversion canals built in Nakhon Pathom will prevent the Tha Chin River spilling to the urban dwelling areas and be diverted on to the sea.

Critical areas are are Khlong Ngiew Rai in Nakhon Chaisi district, Khlong Song Khanong and Khlong Thakham in Sampran district.