BEIJING - Beijing will build a 1,000 km suburban rail network as part of a transportation overhaul to integrate the Chinese capital with neighboring cities, the city's transport director said Monday.

"Inter-city rails and highways to connect a cluster of cities around Beijing and a suburban rail network will help expand the reach of the 1,000 km subway network within the city," said Zhou Zhengyu, director of Beijing Municipal Commission of Transport.

Beijing's municipal government said over the weekend that it will partly move to the city's eastern suburb of Tongzhou, a 40-minute drive away from downtown Beijing, bringing the city's functions away from the downtown area, which has been increasingly pressured by overpopulation.

Building a suburban rail network will make it easier for people to commute to the capital from neighboring cities and is deemed by authorities as the first step toward guiding more people outward to alleviate traffic congestion, pollution and other distress on the capital.

Authorities aim to move 15 percent of city dwellers out of the city center and cap population in the city at 23 million by 2020. The city's population as of the end of last year stood at 21.5 million, more than half of which live in downtown Beijing.

In December, Beijing formed a transportation investment company with neighboring municipality Tianjin and Hebei province to fund construction of transportation infrastructure linking cities in the region.

The overhaul also includes connecting dead ends of existing highways and allowing commuters to use a single pass for public transportation across Beijing, Tianjin and four other cities in Hebei province.