More than 70 young people and staff from a drug rehabilitation centre in Chi Ma Wan, on Lantau, had to spend three hours in the cold and rain at the end of an outing to Cheung Chau last night after being refused a boat to take them back. Jacob Lam Hay-sing, head of the centre, said officials from the Marine Department told them they could not make the trip by sampan for safety reasons, even though this has been their only method of transport since the isolated centre was built in 1993. An angry Mr Lam said three of the youngsters, one suffering from an hereditary blood disease, had to be sent to hospital after being stranded in the open for so long. The group, involving reformed addicts as young as 12, had made the trip to Cheung Chau for a rare reunion with their parents with Lunar New Year approaching. Mr Lam was told two months ago that they could no longer make the trip by sampan, but he said the Marine Department told him it could not find anyone willing to offer a transport service for them. 'We begged and begged and finally, five sampans promised to take us to Cheung Chau,' he said. 'Just when we arrived, officers from the department discovered us and warned all sampans in the area that they were not allowed to take any passengers.' The group was finally able to return to the centre at 11.30pm after the Home Affairs Department and the Narcotics Division managed to find a licensed boat. The Marine Department said that only licensed vessels were allowed to take passengers and that no sampans in the area had obtained such a licence. 'We understand the urgency of the matter, and we are trying to help them,' a spokesman said.