This Chinese business hub is doing more to attract young migrant workers to replenish a labor pool that has become smaller as the local population gets older and the birth rate remains low, a senior population official has said.

"Shanghai is faced with a serious aging problem, and the birth rate is still at a very low level," said Xie Lingli, director of the Shanghai Municipal Population and Family Planning Commission, at a population meeting on Wednesday.

"In this regard, the city's future prosperity will have to depend largely on the migrant population."

Xie said the number of Shanghai workers who are between the ages of 16 and 59 will drop from 9 million to 8.3 million by 2015, largely because too few babies are being born to replace workers who are getting old.

"We are looking at encouraging more young workers, especially those between the ages of 25 and 35, to come here to give balance to the local population, and to help maintain the city's prosperity," she said.

According to the commission, the official average life span of Shanghai's registered population was extended to 82.13 years in 2010. The city then contained more than 3 million people who were 60 years old or older. Together, they accounted for more than 22 percent of the total registered population. According to estimates, that figure will rise to 28 percent by 2015 and will represent a third of the city's entire population by 2020.

Meanwhile, the low birth rate also bodes ill for efforts to maintain a balance in the city's population. Shanghai now contains about 1.17 million officially registered children who are 14 years old or younger. Those in that group account for about 8.3 percent of the registered population in Shanghai, whereas they make up 18.5 percent of the population of China and 27 percent of the world.

The city's family planning policy has prevented the births of about 7 million people during the past 30 years, according to media reports.

Earlier this year, local Chinese media cited the most recent national census, conducted in November, when reporting that the city's population had likely reached 23 million, a figure that accounted for 9 million migrants.

Recognizing that Shanghai's decision to rely more on migrant labor is likely to lead to further crowding, experts are advising authorities to do more to manage the population and to conduct careful urban planning.

And there are other population troubles to worry about.

From 2013 onwards, more than 80 percent of Shanghai's increasingly older population will be composed of parents of only-children. To ensure such parents can live comfortably in their old age, when they cannot expect to have support from a group of children, the city is looking at offering them more public aid.

Previous reports have said Shanghai will be one of several regions where test policies will allow more couples to have a second child.

Officials did not comment on the reports, only saying Shanghai's policy will be adjusted in accordance with the central government's guidance.