A new report from the United Nations Population Fund says Asia's urban population will double by 2030, increasing pressure on city resources and the environment. The U.N. agency says cities need to improve social services and urban planning to cope with the expected boom. Daniel Schearf reports from Beijing.

The United Nations report says that in the next quarter century, Asia, which is home to two thirds of the world's people, will see its urban populations double to 2.6 billion.

Bernard Coquelin

Bernard Coquelin is the China representative for the U.N. Population Fund, which issued its annual report on Wednesday. He says the urban expansion is necessary for economic growth, but he warns it will challenge social services.

"Urbanization can and should be a force for good," said Coquelin. "We should bear in mind that no country in the industrial age has every achieved significant economic growth without urbanization. At the same time, [the] city also concentrates poverty and misery. The number of urban poor is growing at an unprecedented scale."

Coquelin says the urban poor may soon account for one in six city dwellers. The U.N. report says city governments need to start providing more social services and support for the poor now if they want to avert future problems, such as inadequate sanitation, overcrowded schools and packed roads.

The report says urban expansion will mainly be caused by natural population increases in mid-sized cities. But a large part of the growth comes from migration, especially in China and Vietnam.

In China, migrant workers from rural areas are building modern cities. Coquelin says the biggest challenge is ensuring migrants receive the same benefits and public services as permanent city residents.

"It's just to be sure everyone can have access to basic services, which is basic human rights to be sure all people, individuals and families or couples can have access to these kinds of services provided in the cities, which are always higher quality than in the rural areas," he said.

The U.N.'s annual report says that next year, for the first time, most of the world's population will live in cities. Along with rapid urbanization in Asia, the report says that Africa will see populations in its cities double in the next quarter century.