A bus plunged down a steep hillside, killing its driver and injuring 20 passengers in Thailand.

The double-decker bus was en route from Bangkok to Chiang Khan when it veered off the road at the Suan Pa Dong Lan intersection in Nong Thum Subdistrict, Chum Phae District, Khon Kaen Province, on December 27 around 6:30 am.

The vehicle was carrying passengers returning to their hometowns for the New Year celebrations when the crash occurred.

Authorities launched a rescue operation, transporting victims to Chum Phae Hospital for treatment.

Officials confirmed the driver, Wanchai Pongkhan, 52, died at the scene. Investigators believe he may have fallen asleep while driving.

Police Lieutenant Lante Chanabua of Chum Phae Police Station said the bus carried 36 individuals, including the driver, crew, and passengers. Most sustained minor to moderate injuries, while four were in critical condition.

He noted no skid marks on the road, and parts of the bus were found scattered in the forest, with the front smashed into a tree.

The policeman added: 'Passengers with minor injuries were able to climb down from the window before being rescued by the rescuers.'

Despite being one of the wealthiest countries in Asia, Thailand suffers from chronic underinvestment in its highways and education, contributing to its poor road safety levels. Only a handful of African countries are worse.

Thailand has one of the world's worst road safety records. Ministers have set the goal of reducing fatalities from 32.7 deaths per 100,000 people to 12 per 100,000 people by the year 2027.