Schools should be compelled to check if their teachers have been convicted of sex offences, child advocacy groups say. School authorities should also put aside reputational concerns and report complaints of sexual abuse or harassment to the Social Welfare Department, the non-governmental groups say. The issue is in the news after the Canadian International School in Wong Chuk Hang fired and sued a teacher who it claims failed to disclose a harassment complaint lodged 12 years earlier. In 2011, the government introduced a sexual conviction record check service for people working with children. But employers can choose whether to make new hires undergo checks, and there is no option to check serving staff. "This administrative measure is not mandatory, but it should be," said Jessica Ho Oi-chu, director of Against Child Abuse. Michelle Tam Chi-yun, executive director of the End Child Sexual Abuse Foundation, said: "There's a loophole, because only newly employed teachers need to do this record check. But existing employees should also go through this." The Canadian school case centres on Sanjay Lalwani, a teacher hired in 2008 and dismissed in April after the complaint - in connection with his work at Kennedy School, an English Schools Foundation institution in Pok Fu Lam - came to light in October. The Canadian school said it made background checks when hiring the teacher. READ MORE: "Sex case" teacher sacked by Canadian International School quits Hong Kong youth rugby role "The school did contact the four referees put forward, three of whom were current or former employees of Kennedy School. None of them referred to the complaint or the circumstances under which his contract was terminated," it said. It was not clear whether Kennedy School reported the 2003 complaint to authorities. The ESF declined to discuss the Lalwani case on privacy grounds. The Canadian school filed a High Court writ against the former teacher this month. Steve Lam, father of an eight-year-old at the ESF's Bradbury School, was "disgusted" by the foundation's failure to disclose the case. "I have to question what other serious complaints the ESF have kept confidential about their schools' staff," he said. "I realise that the ESF needs to protect its reputation, but when that comes at the cost of physical and mental damage to children and adults then it is truly unacceptable." The ESF declined to comment on Lam's remarks. Schools in Hong Kong are not mandated to report sexual abuse or harassment cases to authorities, which means such matters might be settled quietly. "Some schools have different procedures to handle the cases, and some principals are concerned that the incident might affect their reputation," Tam said. But "the welfare of a child is more important than their reputation. They have the obligation to report the case to the police or the Social Welfare Department". Ho noted the procedural guidelines for handling child abuse issued by the Social Welfare Department advise schools to report cases to the authorities. The Education Bureau said it would contact a school and provide assistance if it became aware of any such cases. If criminal activity was involved "the school should report it to the police with the consent of the victim". Last year , 285 cases of sexual abuse against children were reported to the Social Welfare Department, of which 10 involved teachers and 25 involved tutors or coaches.