Separating twins could lead to problems, the health chief said yesterday, after a case came to light this weekend in which a mentally ill woman spent days with the corpse of her twin sister in their Tin Shui Wai home. The elder sister was believed to have slipped when using the toilet and died two or three days before discovery. Though she also suffered, less severely, from a mental illness, she had been taking care of her sister for years. The twins were found on Saturday morning when firemen broke into the flat on the fifth floor of Yan Lok House, Tin Yan Estate, at about 9am after reports by neighbours of a bad smell. The body was on the floor of the bathroom. Police said the surviving sister was physically frail when they found her sitting on the sofa in the living room. She was admitted to Tuen Mun Hospital in serious condition, though yesterday a Social Welfare Department spokesman said she had become stable. When asked whether it was appropriate to have let them take care of each other, Secretary for Food and Health York Chow Yat-ngok said many twins had a strong dependence on each other. 'If they are separated, it may lead to other problems,' Dr Chow said. 'But each case is different. Initial inspection showed that both of them were in stable condition. They did not show any special symptoms before the incident showing that they needed special care. 'But of course it's undesirable if their condition turns bad without anyone noticing it,' he said. When asked if there were enough beds for psychiatric patients, Dr Chow said that although the Hospital Authority had cut between 300 and 400 beds in the psychiatry department, occupancy was 80 per cent, showing resources were sufficient. The director of Social Welfare Department, Patrick Nip Tak-kuen, said its medical social workers had followed up the sisters' case after they were discharged from Castle Peak Hospital's Tuen Mun Substance Abuse Clinic at the end of 2004 and early in 2005 until early 2007, when their conditions became stable. He added that the department had in March test-run a new service supporting discharged mental patients in Tin Shui Wai.