MORE than 500 allegations, rumours and complaints are under investigation by the inquiry into the controversial operation against 1,500 Vietnamese at the Whitehead Detention Centre. The nature of the inquiry demands that all evidence placed before it in written and oral form must be thoroughly examined before the final recommendations and findings are made on June 10. More than 200 letters from inmates of Whitehead and High Island detention centres will have to be translated and statements taken from the hundreds of Vietnamese who claim to have suffered injuries during the April 7 raid when 557 canisters of tear-gas were fired. While the investigation is under way, the Government has agreed to a request from the two justices of the peace leading the inquiry that none of the Vietnamese moved in the operation be deported to Vietnam. It is understood that JPs Andrew Li Kwok-nang QC and Professor David Todd, who were appointed by the Governor to lead the inquiry, were concerned that vital evidence could be missed if people were forcibly repatriated. On the day of the operation, the Government claimed only one person was hurt. Several days later it admitted that more than 200 had sought medical treatment. Dozens have complained they were beaten by Correctional Services Department (CSD) officers and police during and after the operation. Many people are continuing to lodge formal claims of assault, which police have begun investigating. However, fears are already being expressed that positive identification of any police or CSD officers involved in assaults could be a problem for the inquiry team. One insider said very few people had any means of identifying who assaulted them except some of the 21 now being held in Upper Chi Ma Wan. That group was officially placed there for ''management reasons'' because they were the leaders in Section 7 of Whitehead where the raid took place. Mr Li and Professor Todd have already visited the Chi Ma Wan group and will return next week for the arduous task of taking statements. And, while the probe continues into the incident in Section 7, tensions in the adjacent Section 8 of Whitehead are mounting daily. Visitors to Section 8 report that ''the stakes are up'' and the Government will be faced with a decision in the near future as to how to defuse the situation. Claims have already been made that tear-gas was deliberately launched into Section 8 during the all-day raid. At High Island, to which most of the Section 7 inmates were transferred, there are continuing complaints of medical problems two weeks after the operation. The British Red Cross clinic at the camp continues to be kept busy but the number of burns cases has dropped to a trickle. In the days immediately after the operation, hundreds of inmates sought treatment for burns they said were caused by the tear-gas, mace and ''pepper fog'' tear-gas machine used by the 1,250 officers involved in the operation. Refugee Concern spokesman Pam Baker said she had received numerous letters from former Section 7 detainees describing the day of the operation. ''It is very important that they [the Vietnamese] stick to telling only what they saw with their own eyes and heard with their own ears,'' she said. ''We must make sure justice is done and it's hard for these people to understand that they must stick with only what they know.'' Ms Baker said the inquiry into the Whitehead operation offered an opportunity for the Vietnamese to make a point. Inquiry secretary Anthony Bennett said several days would be spent at High Island taking statements with the assistance of interpreters. ''We realise it will involve talking to hundreds of people because everyone is going to want to have their say, but that's exactly what we are here for.'' He also said that as the inquiry progressed, meetings would be held by inquiry staff to determine new directions, problem areas and to make progress assessments. ''We will need to take stock of things from time to time to ensure that nothing is missed.''