BEIJING - China will stick to its national family planning policy, but improve its policies in aspects like reproduction, migration and gender equality to achieve a more balanced and sustainable population development, said a senior official.

"A comprehensive plan will be formulated to realize a healthy population growth, improve levels of government competence, optimize population structure and guide rational population distribution," Li Bin, minister of the National Population and Family Planning Commission, said during an interview last week.

She said China will stick to its family planning policy for a long time, contributing to China's goal of building a well-off society.

Under the policy over the past three decades, the country has made a historic transition from one featuring a high birth rate and high population growth rate to one with a low birth rate and low rate of population growth.

"That hasn't come easy, and thanks to people's great understanding it has helped China achieve rapid economic growth and the gradual establishment of a social welfare system," Li said.

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Li, however, also conceded that in the coming decades, the country faces demographic challenges including an aging population, imbalance of sex ratio and high rates of birth defects in certain areas.

The number of people above 60 years old is expected to reach 200 million sometime between 2011 and 2015, and the population will keep rising sharply from 2016 through 2040, which may put a great strain on the social security system, experts have estimated.

"In order to deal with an aging society, China will implement an active, healthy and harmonious strategy," Li said, adding that the country will establish an old-age security system that is family-centered, community-based and institution-supported, and at the same time, establish a system which benefits development, welfare, happiness and harmony in families.

Regarding the imbalanced gender ratio, largely due to the traditional preference of boys over girls, Li said authorities will strictly prohibit abortions for sex selection and better implement policies encouraging gender equity over the long term.