NINETY per cent of 200 girls - most of them aged 13 and the youngest 12 - being held on remand in the Ma Tau Wei Girls' Home have venereal diseases, but there is only one nurse on duty, it was claimed yesterday. A staff member last night accused the Social Welfare Department of covering up the truth about the poor conditions in the centre. Overcrowding and the lack of sufficient medical facilities have reached critical levels since the police began raiding karaoke bars and arresting underage girls found in them. But the Social Welfare Department maintained yesterday that hygiene at the home in Ho Man Tin was good and the girls' behaviour had not deteriorated because of overcrowding. The remand section of Ma Tau Wei has a capacity of 100, but there are now nearly 200 inmates. More places will likely be needed as police continue to crackdown on karaoke lounges, many of which are fronts for gangs offering sex with underage girls. The raids have mainly taken place around Yau Ma Tei, Tsim Sha Tsui and Mongkok. The staff member told the South China Morning Post that although the department had taken emergency measures by redeploying an extra 13 social workers to the home, at least four more were needed. ''Ninety per cent of the inmates are suffering from venereal diseases and a few of them are pregnant. But social workers do not have sufficient medical knowledge to take care of them,'' she said. ''The girls' rooms are smelly and unhygienic with cockroaches. The conditions could make their diseases, which are serious, even worse.'' There was only one nurse on duty at any one time during the day and no nurse was available in the evening, she said. She added that social workers were not provided with adequate training on handling girls with sexually transmitted diseases because of staff shortages. The social workers did not know how to answer girls' questions about their diseases, she said. Nor were they given any indication on how to handle HIV-positive inmates, a former worker in another juvenile home said. He said there had been a case in his home in which a girl aged about 15 to 16 claimed to be a carrier. ''The social worker in charge was told to keep the girl in isolation when she asked the home's superintendent what to do,'' he said. ''There was no effort to verify whether she was really HIV-positive, although she claimed she was under treatment. ''The girl was not allowed to join the activities with other inmates or to have meals with them. She could go outside the room for an hour every day with staff keeping an eye on her from a distance,'' he said. A Social Welfare Department spokesman rejected the allegation. ''It is untrue, we do not keep girls with diseases in isolation as they would be taken care of by a registered nurse,'' she said. However, because of confidentiality, she declined to discuss whether there were records of venereal diseases or AIDS. The spokesman said that apart from a registered nurse, there were visiting medical officers to look after the girls every week and the police would escort patients to clinics if necessary. The staff member at the Ma Tau Wei home said the frequency of fighting and other disciplinary problems had increased because of the influx. ''There are not sufficient disciplinary arrangements to control such large groups,'' she said. She said a fight between the girls over trivial matters had occurred on Sunday, but the department had denied this. ''Staff morale has been adversely affected by the sudden increase in workload - many of us want to go on holidays,'' she said. But the home's superintendent told the department last night that ''staff morale was high'' and the hygiene conditions improved after the probation section was vacated to give additional bed spaces for the girls on remand.