Eight people were killed while 30 others were injured in a bus crash after the driver allegedly fell asleep while doped up on methamphetamine.

The tour bus operated by Thailand’s state-run transport company smashed into a concrete barrier before hitting a bridge pillar in Saraburi province on Saturday afternoon March 12.

Driver Narinsart Hongsa, 30, was taking passengers to Bangkok from Roi-Et province when he is believed to have fallen asleep on the wheel, according to police.

Narinsart initially denied falling asleep and said that one of the tyres might have burst but test results allegedly showed that he was high on methamphetamine during the crash.

Police Colonel Chetchai Chetsiri said: 'The driver later confessed to us that he was high on methamphetamine while driving. We have filed two charges against Narinsart for being intoxicated while driving and for causing property damage and deaths to others.'

At the scene, the cement block barrier was completely smashed while the vehicle's interior, the front right wheel, and the bar area on the right side of the car was also damaged.

The driver was only slightly injured with a wound on his mouth and a broken tooth. His blood and urine tests allegedly showed that he was intoxicated with illegal drugs at the time of the accident.

Officers took Narinsart into custody for a thorough investigation while the injured passengers were taken to Saraburi Hospital, Saohai Hospital and Kaeng Khoi Hospital for treatment.

The injured passengers and the relatives of those killed in the crash will now be compensated by the transport department's insurance company while investigations are ongoing, officials said.