TAIPEI • The deadly bus crash in Taiwan that killed an entire Chinese tour group was caused by a "suicidal" driver who intentionally set the vehicle on fire, investigators said yesterday.

The authorities had earlier said that the driver, Su Ming Cheng, had been drunk when his bus caught fire and rammed through an expressway in July, killing himself and 25 others on board.

Minutes before the incident, Su, who was driving the group to the airport, had poured petrol over the driver's seat and on the floor near the exit before sparking the fire with a lighter, investigators said.

"(Su), who was drink driving, committed suicide by pouring gasoline and setting a fire, killing other passengers," Taiwanese prosecutors said in a statement yesterday.

The probe uncovered dozens of phone records between Su and his family in the days before the crash, with relatives pleading with him not to commit suicide.

A text message from his sister read: "Don't you love the three children in your family?

"Don't let them be ashamed. If you do this, it will bring shame to us all."

The Taiwanese driver was also described by the authorities as a regular drinker with a violent history.

Su had been hit with separate lawsuits for scuffling with a tour guide and sexually assaulting an unnamed victim.

In both cases, investigators said he was intoxicated.

"Because of this, Su was depressed," said prosecutors.

In May, Su was briefly suspended by his employer for fighting with another tour guide.

Su's job driving the group from China's north-east city of Dalian in July was his first after the suspension, according to officials.

The incident prompted Chinese authorities to demand that the island take measures to improve safety for mainland visitors.

AGENCE FRANCE-PRESSE