The accident happened around the same time as another bus crash in Beijing in which two Hong Kong people died, and has prompted renewed concern over road safety across the border.

Travel agency representatives said relatives of the two boys - Choi Man-hin, eight, and Choi Ching-hin, nine - did not tell them of their parents' deaths, fearing it might affect their recovery from head and leg injuries received in the accident. Hospital staff said they were in a stable condition, China News Service reported.

Their parents, Choi Yam-hung, 43, and Hui Ping, 34, were killed when a tour bus carrying 22 passengers and driver Yang Shaoxiong skidded and overturned while approaching a bridge on a hairpin bend in Longsheng county, Guangxi, at about 10am on Friday.

Eight injured travellers are still recovering in three hospitals in Guilin, while seven with minor injuries flew back to Hong Kong yesterday and were sent to Princess Margaret Hospital. With the exception of a 19-year-old woman who remained in stable condition, they were all discharged later.

Lying on his bed at the Guilin Hospital of Traditional Chinese Medicine, orphan Ching-hin could not remember what happened.

'I sat in the second last row and my parents were in the last [row],' he said. 'Our heads hit the ground quite hard but I can't really remember anything about the accident.'

Traffic police in the county said rain and slippery roads were factors behind the accident, Xinhua news agency reported.

But the guide for the five-day-tour organised by Miramar Express said it was neither a rainy nor misty day.

'I don't believe the bus was speeding,' she said. 'But we were going down a slope and reached a U-shaped turn. The driver could not make the turn and apply the brakes before crashing [into the railings].'

Some of those who returned to Hong Kong yesterday echoed her view that the driver could not apply the brakes.

Guangxi Tourism Administration said an investigation was continuing.

Hong Kong Travel Industry Council executive director Joseph Tung Yao-chung said it had written to the administration calling for an investigation.

Given the rising concerns over the welfare of Hong Kong residents travelling overseas, Central Policy Unit chief Lau Siu-kai yesterday revealed the government was studying ways to establish a formal mechanism to help them in emergencies.

In Beijing, the widow and mother of a father and son killed in a collision between a tour bus and a truck on Friday, and two surviving young children, were at a hotel after leaving Qinghe emergency centre.