Brake failure was the suspected cause of the accident.

According to Sai Yok police Lt-Colonel Supparerk Chaiphum-

sakul, the bus was found against a tree two metres below the level of the Wangpho-Sai Yok road.

He said the large tree had prevented the vehicle from plummeting the 100-metre depth of the gorge.

Supparerk assumed the brakes had failed, causing the bus to flip twice before coming to rest against the tree.

It was carrying 45 employees of Phetchaburi-based bed-manufacturer World Bedding to their annual meeting at the Sai Yok View Hotel in Kanchanaburi.

Nine people, including the driver, were pronounced dead at the scene, and another nine died on the way to hospital.

The 20 injured passengers were being treated at a number of hospitals in the province.

Company-owner Vimolrat Padungphan had been travelling separately to the meeting.

She expressed sorrow at the accident and the deaths of her workers.

The company will cover hospital expenses and provide compensation for victims and their families.