The driver of a bus that crashed killing 20 people in the country's worst road accident had two outstanding arrest warrants for reckless driving, initial results of an investigation showed today.

Rohizan Abu Bakar, 28, who was among the dead, also had 13 summonses from police, the official Bernama news agency said.

It was not clear however why he had managed to evade arrest or how why the operator of the express bus hired him despite his record.

According to transportation authorities, Rohizan apparently fell asleep at the wheel while driving down a hill on a highway in Penang.

The vehicle then hit a road barrier, skidded and overturned before falling into a ditch.

Twenty people, including two Indonesians, a Nepalese and a Vietnamese were killed in Monday's accident. Nine others were critically injured.

Prime Minister Abdullah Ahmad Badawi blamed human error and carelessness, and told authorities to carry out an investigation for possible prosecution of those culpable.

Grieving

"Drivers of public vehicles must be certain that they are as healthy as pilots to ensure the safety of the passengers," Abdullah said on Bernama late Monday.

"It must also be ensured that they do not subject themselves to something harmful, do not drive more than a certain number of hours. Besides, they should have several years' driving experience."

Authorities have already suspended the bus company from operating.

Meanwhile grieving relatives said they would take legal action against the bus company.

"I will sue them. I will discuss with a lawyer for further action," said Tony Siew, whose son Siew Ken Meng, 21, was among those critically wounded.

He said his son, a mechanic, needed life support in hospital. "He was heard writhing in pain," he added.