Hong Kong's population crisis is likely to worsen as a survey showed Thursday that nearly four in 10 women want only one child or no children at all.

The study by the Hong Kong Family Planning Association found a growing trend toward childlessness in the wealthy city, which already has one of the world's lowest birth rates.

Twenty-six per cent of 1,500 women interviewed said they wanted only one child compared with 10 per cent in 1992, and 13 per cent said they wanted no children, compared with 5 per cent in 1992.

Less than 50 per cent said they wanted two children, a decrease of more than 10 per cent from 1992 when a similar large-scale survey was conducted.

Hong Kong's birth rate is already less than one child per woman, compared with around three in the 1980s, and the government is facing twin problems of an ageing population and a general labour shortage.

Couples in Hong Kong are increasingly unwilling to have big families because of the high-rise city's limited living space and notoriously high living and education costs.

Professor Paul Yip, who headed the survey, said another major factor was that women were marrying later and delaying having children because of careers and the perceived expense of children.

Forty per cent of women married for four to five years still had no children and the number of women aged 35 to 39 who were still childless had risen significantly, the study found.

Almost one in three women aged 35 to 39 in the city of 6.9 million said they had fewer children than they wanted but many said they did not want to risk a late pregnancy.

Hong Kong Chief Executive Donald Tsang three years ago appealed to couples to have three children each, but surveys and censuses indicated that few couples are so far willing to take his advice.