Swathes of central Thailand were left underwater after heavy rain from Typhoon Ragasa battered the region.

Aerial footage shows the widespread flooding as the swollen Nan River overflowed into communities in Phichit province on September 23.

Officials have declared 12 districts disaster zones as the deluge overwhelmed water pumps, leaving some 336 villages swamped.

Authorities warned of continued flooding in the Yom River basin.

The Thai Meteorological Department said today that Typhoon Ragasa, which killed at least five when it tore through the Philippines this week, was located southwest of Hong Kong with maximum sustained winds of around 108.7 mph (175 kph).

The storm was expected to pass south of Guangdong, China, and enter the Gulf of Tonkin on September 25, weakening into a tropical storm before making landfall in northern Vietnam.

Ragasa was predicted to rapidly weaken due to a high-pressure system over China on September 25 to 26.

Forecasters said the typhoon was not expected to touch down in Thailand, but warned that it will strengthen the monsoon trough across the country's northern region, causing heavy rain.

Residents in the affected areas were advised to be vigilant of flash floods, especially along waterways near foothills and lowlands.