Thailand's worst monsoon floods in decades have killed 224 people and affected three quarters of the country, including part of the ancient city of Ayutthaya, officials said Tuesday.

Authorities were meanwhile battling to stop the floods reaching the centre of low-lying Bangkok, as forecasters warned of more wild weather to come.

"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.

Two months of flooding have inundated 58 of 77 provinces -- with 25 still severely affected -- and damaged the homes or livelihoods of millions of people, according to the government.

Wat Chaiwatthanaram, one of Ayutthaya's best-known temples, has been closed to visitors after a makeshift dyke was breached at the former capital, a popular tourist destination north of Bangkok.

"The water level inside the temple grounds is now 1.50 metres (five feet)," 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.

The northern city of Chiang Mai, another popular tourist destination, has also been badly hit.

"The current flood situation is the worst that I have ever seen and it will last until the first week of November," said independent flood expert Royal Chitradon, director of Thai Integrated Water Resource Management.

"There is a problem of prolonged flooding in central provinces because roads and cities have blocked natural waterways."

Royal said several reservoirs are already full and the western and eastern outskirts of Bangkok are at risk of flooding because of another approaching tropical storm.

Last week the government announced the deployment of about 10,000 soldiers, backed by 500 military vehicles and more than 100 boats, to help victims.

Army bases will also take in evacuees, the military said Tuesday.

In total about 14.8 million acres (six million hectares) of land have been inundated around the country, said chief government spokeswoman Titima Chaisang.