More than 250,000 people across several provinces on the Chao Praya river basin were impacted by the floods this week, the Department of Disaster Prevention and Mitigation said in a statement.

Two men drowned in Ayutthaya province, north of the capital Bangkok, while moving their belongings through floodwaters, and another was killed after his rowboat capsized in Phetchabun province.

In Phichit province, a 17-year-old girl was killed driving her motorbike through a flooded area.

The meteorological department forecast more heavy rain in Thailand's north, central and eastern provinces, including Bangkok, until Friday, with the possibility of flash floods.

Thailand regularly records heavy rainfall from June to September, but experts say human-induced climate change has intensified extreme weather, making conditions increasingly unpredictable.

In northern Thailand last month, five people were killed and 15 were injured in landslides and flooding triggered by Typhoon Kajiki.

Kajiki tore roofs off thousands of homes in Vietnam, killing several people and forcing tens of thousands to evacuate.

Widespread flooding across Thailand in 2011 killed more than 500 people and damaged millions of homes around the country.