China, the world's most populous country, has pledged to persist in its birth control policy as the population of the planet reached six billion Tuesday.

　 "China will continue to enforce its effective family planning policy in the new century in order to create a favorable environment for further development," Chinese Premier Zhu Rongji announced in Beijing Tuesday.

　 In a letter to a Beijing meeting marking the World Day of Six Billion, Zhu said that without China's efforts, the world's population would have passed six billion four years ago.

　 He added that more than 300 million births have been avoided thanks to the fundamental state policy of the past three decades, which has also benefited the country's economic growth and the improvement of people's lives.

　 Despite this success, however, China remains vigilant on the issue of population since an average of 10 million people are born every year, which means even heavier pressures on natural resources, the environment, employment and the social security network.

　 Home to a fifth of the world's people now, China plans to keep its population under 1.4 billion through 2010, and 1.6 billion by 2050, with the aging and working populations reaching a peak at that time.

　 "Any laxity on our part will lead to a rebound of the birth rate. Our task is therefore long-term and arduous," warned Zhang Weiqing, director of the State Family Planning Commission.

　 Speaking to Tuesday's meeting at Beijing's Great Hall of the People, Vice-Premier Li Lanqing urged the combining of family planning programs with sustainable development strategies.

　 "While carrying out these programs, we should achieve the integration of economic growth, poverty eradication, education, environmental protection, and the improvement of women's social

　status," Li said.

　 Tens of thousands of family planning workers and volunteers conducted publicity activities and services nationwide focused on the theme "Population and Sustainable Development."

　 "We must be aware of our responsibility to future generations. What we do now and in the near future will have a major impact on life throughout the 21st century," said Kerstin Trone, deputy executive director of the United Nations Population Fund, at the meeting.