One in 10 employees earns less than $4,500 a month full-time, with staff working increasingly long hours as the gulf between rich and poor widens, a survey released yesterday found. The study, commissioned by charity group Oxfam Hong Kong and conducted by researchers from City University of Hong Kong, looked at Census and Statistics Department figures from 1996 to 1999. It found that the number of marginal workers - the unemployed, part-time workers or those earning less than $4,500 per month full time - had risen 42 per cent from 450,000 in 1996 to 640,000 in 1999. Of these, 320,000 were working full-time but earned less than $4,500, with 70,000 making less than $3,000 a month full-time. Some 180,000 of them worked more than 50 hours a week. The average income in Hong Kong is $10,000 a month. Overseas domestic helpers, who number about 200,000 and who have a government-set minimum wage of $3,670, were included in the survey. Researcher Dr Wong Hung of the university said the cause of the low wages was the short-term contract and part-time, temporary work in the wake of the Asian economic crisis. 'The workers are locked in a vicious cycle in which people are unemployed and seeking employment, but the jobs they get pay little and demand long hours,' Dr Wong said. 'We think the Government should consider the introduction of maximum work hours and a minimum wage to protect this group, which has been neglected and forgotten.' Oxfam executive director Chong Chan-yau said: 'Hong Kong has never had such a huge gap between rich and poor before. We can't tell ourselves we're in economic recovery if we have such a gap.' Democratic Party legislator Fred Li Wah-ming said: 'I have come across a toilet cleaner who works 12 hours a day, 72 hours a week and earns $5,000 a month. I think the $5,000-$6,000 salary range is becoming the norm. I don't understand why Hong Kong can't get maximum hours and minimum wage protection. Most other Southeast Asian countries have it.' A government spokesman said: 'The Government has been working hard to promote employees' rights and is devoted to retraining programmes. With the strong economic recovery, we think the employment market will be more optimistic.' Last month, unionist legislator Lau Chin-shek raised a motion to regulate working hours. A similar motion, moved by Democrat Andrew Cheng Kar-foo, was debated by the pre-handover legislature in April 1997.