The policy was effective to boost the economic development and improve people's life, Zhang Weiqing, director of the National Population and Family Planning Commission, said while addressing the opening ceremony of an international seminar on population and development in Beijing.

Zhang said enforcement of the one-child policy and opening to the outside world in the late 1970s allowed China to develop a rapidly growing economy over the past three decades.

In this period, the nation recorded a gross domestic product that grew 9.6 percent on average each year. China's GDP totaled US$2.23 trillion by the end of last year.

The policies also enabled the country to rein in excessive population increases, Zhang said.

However, he also said many issues on population will challenge the country.

China's per capita GDP, which hit US$1,700 last year, still ranked more than the 100th in the world.

A rising population, an unbalanced gender proportion of newborn babies, the expanding aging group and a large migrant population are among the problem the country will have to address, Zhang noted.

Wang Guoqiang, the commission's deputy director, said China's population will have an annual increase of eight million to 10 million in the next more than 10 years.

According to earlier media reports, China's population will peak in the 2030s at 1.46 billion. The number of people older than 60 is expected to reach 174 million by 2010, accounting for 12.78 percent of the total.

Besides, the number of people aged from 15 to 64 years old, who are considered able to participate in work, will rise to 940 million by 2020, accounting for about 65 percent of the total, bringing more employment pressure.