The severe monsoon season in Thailand has now killed more than 200 people in the worst flooding in decades, which has affected 58 of the country’s 77 provinces.
The northern city of Chiang Mai was severely affected last week and as waters move along major rivers, areas closer to Bangkok are being flooded.
A makeshift dyke has been breached at the ancient city of Ayutthaya near the capital, where historic temples are at risk.
“The water level inside the temple grounds is now 1.5 metres,” said Supoj Prommanoch, head of the Fine Arts Office in Ayutthaya.
He said 10 other temples were also flooded but the authorities were confident they could prevent the waters from reaching Ayutthaya’s main World Heritage Park, which is located further away from Chao Phraya River.
Authorities say Bangkok will be at risk of flooding for another month as excess water moves down the swollen Chao Phraya River.
Some 10,000 soldiers have been deployed to help victims.
Army bases will also take in evacuees, the military said.
“It’s the worst flooding yet in terms of the amount of water and people affected,” said an official at the Department of Disaster Prevention and Mitigation who preferred not to be named.
Forecasters warned of more wild weather to come.
They said several reservoirs were already full and the western and eastern outskirts of Bangkok are at risk of flooding because of another approaching tropical storm.