Security guards and cleaners at Hong Kong universities are paid two-thirds less than counterparts in England, while lecturers are paid twice as much as those teaching at Cambridge and Oxford, a study has revealed. The study, by the Hong Kong Cleaning Service Industry Workers' Union and the Hong Kong Buildings Management and Security Workers' General Union, looked at pay and benefits at the eight local universities by studying job advertisements. All the tertiary institutions, except the Chinese University, contracted out their cleaning and security services. Cleaning company ISS, which provides cleaning services at Baptist and Lingnan universities, paid its workers the least - between $3,850 and $4,000 a month. The cleaners must also work 10 hours a day and get only three days off a month. Most university security guards must work 12 hours a day as the roster has only two shifts, the unions said. On average, university cleaners are paid about $18.50 an hour, while security guards receive about $20 an hour. In England, cleaners at colleges are paid up to $56 an hour and security guards about $60. Their salaries work out at more than $10,000 a month. The study showed that Hong Kong professors earn between $102,800 and $127,155 a month, while lecturers in Cambridge and Oxford are paid between $52,000 and $67,700. Suzanne Wu Sui-shan, chief executive of the Cleaning Service Industry Workers' Union, said universities usually contracted out cleaning and security services to the lowest bidder without setting a minimum salary. She said ISS had also cut cleaning workers' pay from $4,300 to $3,850 a month in the past year. 'The company also forces cleaning workers to work overtime without paying them properly and they end up only having three days off, which is illegal.' Ms Wu said the union had filed a complaint with the Labour Department. She also urged universities to blacklist contractors mistreating workers.