POLICE were last night questioning a 59-year-old man about the fatal stabbing of a man in Kwai Chung over what appeared to be a squabble over rent. Police and ambulancemen were called to the 14th floor of Hing Lok House, Kwai Hing Estate, Kwai Chung, shortly before midnight on Saturday by a neighbour who overheard an argument. Wong Loi-sau, 57, was found lying in a pool of blood with stab wounds to the neck. He was certified dead by paramedics. A blood-soaked knife was found in the apartment Wong shared with a friend. A police spokesman said the suspect was arrested and was helping with inquiries. 'We have had problems understanding this man and have requested the assistance of the Social Welfare Department,' he said. 'It is understood there had been an argument concerning rental problems.'