China is writing a strategy to prevent potential population problems.

The first 50 years of the new century will be crucial for the nation's population growth, senior Chinese official Yu Xuejun said.

The challenges that the country will face include a lack of educated and skilled workers, a growing number of migrants and a disproportionate sex ratio at birth.

The challenges will all add to the risk of social and economic problems, said Yu, who is the director of the Department of Policy and Legislation of National Population and Family Planning Commission.

"All these problems will pose severe challenges to the nation's population and family planning work," Yu said.

In March, Yu's commission organized around 300 scholars, experts and government officials to conduct a study about population strategy.

Based on basic data about population size and structure, the researchers will work out a medium-and-long-term blue-print for the nation's population development and put forward proposals for policy makers.

"The research is well under way and the preliminary outcome is being evaluated," Yu said.

The study also looks at employment, population distribution and people's health.

"Priority will be given to controlling population growth and stabilizing low fertility since overpopulation is still a serious problem in the country," Yu said.

"We will take into account improving education, structure and distribution of the population," he added.

China implemented its family planning policy in the 1970s, when poverty and dramatic population growth risked eating up the country's limited resources.

Thanks to the policy, China has maintained a rational population growth rate in line with its economic and social development.

But few policies are perfect and other problems have emerged from China's family planning, including the aging population and gender imbalance resulting from son preference.

The fifth census in 2000 found that the number of people above 65 amounted to 88.11 million in the country, which is 6.96 percent of the total population.

The tradition of son preference has widened the disproportion of sex ratio.

According to official statistics, in the Chinese mainland there are 117 boys born to every 100 girls.

The results could be social insecurities and marriage pressures.

But Yu said that from the perspective of development, family planning will be the nation's long-standing basic policy considering its national conditions.

"China is the most populous country in the world and it will not give up the policy because of the negative effects it may bring about," he added.

The government is still working on some new measures to minimize the negative effects, said Yu.

While formulating the population strategy, the nation is endeavouring to promote the family planning policy by compensating one-child or two-girl families in rural areas.

According to the system, any couple living in the countryside with one child or two girls is entitled to an annual 1,200-yuan (US$145) subsidy once they are over 60 years old.