The figures released by the Census and Statistics Department show that the widest gaps are among plant and machine operators, with men earning a median income of $10,000 a month last year, 81 per cent more than the female median of $5,500. Male shop workers earned 51 per cent more than female colleagues, male craft workers 25 per cent more and male managers and administrators 15 per cent more.

The only sector in which women earned more than men on average was that of 'associate professionals', with female staff earning a median of $16,000 per month, 6 per cent more than men. Male clerks earned $10,000 a month, five per cent more than the $9,500 median salary for women.

The statistics also showed that men with a university degree earned a median monthly salary of $28,000 last year - compared with $20,000 for women graduates.

Overall, men's median salary of $12,000 is 26.3 per cent more than women's $9,500. However, the figures exclude Hong Kong's 210,000 foreign domestic helpers who are paid a minimum of $3,270 a month.

The pay gap was 20 per cent in 2001.

The outspoken former head of the Equal Opportunities Commission (EOC), Anna Wu Hung-yuk, said: 'Hong Kong definitely has not achieved gender equality in the area of employment. We still see a wide pay gap between men and women.

'Some women lose their seniority after they quit their jobs to take care of families. So they end up accepting a lower pay when they return to the labour market,' said Ms Wu, whose term as commissioner ended on August 1. 'Laws are only to set norms and standards. But norms by themselves cannot change the culture.'

Ms Wu warned that the 'glass ceiling' in Hong Kong - as in many other countries - meant women were blocked from reaching the top and so were condemned to lower-paid ranks.

Ms Wu called for more public policies to enhance gender equality at work, such as encouraging more women to enter male-dominated sectors. The same principle should apply to men breaking into female-dominated sectors, she added.

She said the government should set a good example for the private sector. It could, for instance, review and balance the ratio of men to women in different departments. Of the government's 14 top officials, only two are women - Secretary for Justice Elsie Leung Oi-sie and environment chief Sarah Liao Sau-tung.

An EOC spokesman said it supported the principle of equal pay for work of equal value, although it had not received a substantiated complaint about the issue.

Agnes Yeung Koon-chui, co-convenor of the Women's Commission's 'gender mainstreaming taskforce', acknowledged the long-standing pay gap.

She said Hong Kong remained 'backward' in promoting gender equality at work, as major posts were mainly occupied by men in both the public and private sectors. This was despite the fact that more women than men had gone to university since 1998. The taskforce plans to approach private companies to change their culture of male-dominance.

Catherine Tang So-kum, a psychology professor who also carries out studies on gender inequality, said some women agreed to take lower pay, especially in male-dominated industries, simply to secure jobs. 'They tend to lower their salaries to attract employers. However, it becomes a vicious circle,' she said.

Similar pay trends exist on the mainland. A survey by the All-China Women's Federation found that in 1999 the average annual salary for urban women was 7,409 yuan (HK$6,980). Men earned 10,569 yuan, or 42 per cent more.

In the US, men earn 31 per cent more than women according to 2001 figures.