WOMEN residents of Yau Oi Estate in Tuen Mun said yesterday they lived in constant fear of attack following the spate of rapes over the past six months. Some residents said the problem might be more serious than the police realised, because some women were not prepared to come forward and report sexual assaults. Fears grew following the murder of a woman yesterday. She is thought to be the latest victim of a rapist who has attacked five other women in the new town in the past six months. Most women agreed that women were most at risk late at night, but they stressed that at no time of day was it safe to be out alone. Ms Tsang Wah-mui, who works for the Kowloon Dairy, said she never used the lift even though she lived on the third floor of Yau Oi Estate. ''I always walk up and down the stairs, because strangers always seem to be lurking around nowadays,'' she said. ''Maybe it's just me and I don't pretend to be brave, but my heart beats faster when I see people I don't know hanging around the lifts.'' Her daughter, Miss Chan Yuk-keung, a teacher, said: ''Going out after dark means taking a very great risk. Before I go anywhere I tell my parents where I'm going and I call to say I've got there when I arrive.'' She did not like the idea of her parents waiting up for her whenever she went out, but they could not sleep until she was home. The family has been following the advice given in a government announcement on television. Miss Chan calls ahead to tell her parents she is on her way home. ''I forgot just once,'' she said. ''I got back to find my mother hanging over the balcony looking out for me and my father on the ground floor waiting for me.'' Mr Chan Wan-sang, the district board member representing the estate, said he suspected the problem was more serious than police realised. ''At present we know there had been five rape cases at Yau Oi, Tai Hing and Kin Sang estates in the past six months,'' he said. ''These are known cases, but what about the unreported ones?'' He said board members and residents were concerned about law and order in Tuen Mun, a new town with 410,000 people. According to the elected board member, a 30-year-old woman was raped just before Christmas at the adjacent Oi Tak House. Police community relations officer Chief Inspector Philip Kwong Chu-man said police were most alarmed by the similarity of the attacks. In every case the victim had been attacked in a lift or dragged along a staircase. ''The victims were mostly coming home late at night, walking alone and travelling in lifts,'' he said. ''We have identified potential problem spots and we need the public to help us with information, no matter how trivial it is.''