Hong Kong - Hong Kong's population is ageing rapidly because of low birth rates and the reluctance of young mainland Chinese to migrate to the city, a news report said Tuesday.

As China becomes more prosperous, the proportion of young people coming to Hong Kong, population 6.9 million, has fallen from 30 per cent in 2002 to less than 25 per cent in 2008, the South China Morning Post reported.

While mainland Chinese used to scramble to relocate to wealthy Hong Kong, a daily quota of 150 migrants has been met only once in the past five years, the newspaper said.

Last year, the number of mainland Chinese taking advantage of the migration scheme was on average 92 people per day, filling less than two-thirds of the quota.

Fung Hing-wang, Hong Kong's commissioner for Census and Statistics, told the newspaper his department would have to review their population projections because of the unexpected decline in interest in moving to the former British colony.

Hong Kong relies on young people from mainland China to boost its population because of the city's traditionally low birth rate.

Women in the wealthy city have on average only 0.9 babies, compared to nearly three in the early 1980s, even though China's one-child policy does not apply in Hong Kong.

The Hong Kong government has given tax relief to bigger families and earlier this year considered awarding a "baby bonus" to encourage women to have more children.

Birth rates have slumped because of the lack of living space in the densely-populated city, high education costs and a trend to marry late, researchers and officials said.

Government officials predict that if the trend continues, the number of people aged 64 and over will account for a third of the city's population by 2033.

Hong Kong's birth rate of 0.9 children compares to 1.6 in Britain and 1.3 in Germany, and its rate of decline is believed to be the world's fastest. (dpa)