Expecting to see the number of people living in Beijing increase by about half a million people a year for the next 10 years, city authorities are under pressure to bring the ever-expanding population in the capital under control.

Beijing saw its population increase by about 520,000 people a year from 2006 to 2010, a trend that is expected to continue until 2020, Ding Xiangyang, vice-mayor of Beijing, has said.

Such rapid population growth has strained the city's capacity to provide public services and social welfare. The municipal government now considers dealing with the population increase to be one of its central tasks in the next five years, Ding was quoted as saying on Thursday by the Beijing News.

Liu Zhi, director of the municipal commission for population and family planning, said the capital city plans to start using new research projects, databases and monitoring systems to manage the urban population and keep track of the characteristics of Beijing residents.

Liu said measures meant to slow the migration of people to the capital, such as the use of hukou (permanent residence permits), will lose effectiveness over time because of the size of the migrant population in China and because of low fertility rates.

Qiao Xiaochun, a professor at the population research institute of Peking University, said Beijing's increasing population, augmented by a massive inflow of workers seeking opportunities, furnishes a labor force that is greatly needed to ensure economic prosperity.

But the rapid rise in population, coupled with low birth rates in an ageing society, also pose great obstacles to urban planning and sustainable development, Qiao said.

And Beijing cannot overcome these difficulties alone. Cooperation is needed among different regions to make other places more attractive for workers. That will help stem the tide of people flowing into large cities like Beijing and Shanghai.

But Shanghai has an advantage over Beijing. Duan Chengrong, a professor of population studies at Renmin University of China, said Beijing is close to few cities that have strong economies, while both Shanghai and Guangzhou are surrounded by cities with booming economies, which helps to absorb the large number of people moving into their regions.

Duan said the best path forward lies in getting rid of the differences that exist between those living in rural and urban areas. Among the things eliminated should be disparities in personal income, housing, education and healthcare, enabling formerly disfavored cities to become more attractive to urban dwellers.

"Beijing's population is bound to surge because its urbanization rate is still less than 50 percent, which is below the national level of 58 percent set for 2020," Duan said.

And it may be unwise to place a hard-and-fast limit on population increase in Beijing, because economic advancement and technological breakthroughs can enable a city to make better use of space and resources and provide more residents with improved living standards, he said.

Beijing's population reached 19.72 million by the end of 2009, a number which accounted for 7.26 million migrant workers.