BEIJING - Zhang Bing grew up in remote Inner Mongolia, where his family herded sheep and raised chickens. Today he's a manager in a glittering karaoke club 1,000 kilometers (600 miles) away in a booming eastern Chinese city.

Zhang, 26, is part of a huge wave of rural workers streaming into China's cities in search of work and opportunity. A UN report released Wednesday said more than half of China's population - now 1.3 billion people - will be living in urban areas within 10 years.

Government officials say an estimated 150 million people moved to China's cities between 1999 and 2005, providing labor to fuel the country's breakneck economic growth.

"From 1980 to 2030, the population of China will go from being 20 percent urban to almost two-thirds urban. We're in the middle of that transformation. Within the next 10 years we'll cross that halfway mark," said William Ryan, the United Nations Population Fund's information adviser for Asia and the Pacific region.

The agency's State of World Population 2007 report says more than half the world's population will live in cities and towns in 2008, with the number expected to grow to 60 percent, or 5 billion people, by 2030.

Asia is at the forefront of this demographic shift, expected to nearly double its urban population between 2000 and 2030, from 1.4 billion to 2.6 billion.

Zhang moved to Tianjin after high school and earns about US$500 (euro370) a month at the Oriental Pearl karaoke club. He saves two-thirds, and is thinking of opening a store to sell knockoff purses.

He said he expects to have a wife, house and car - "an Audi, definitely" - within 10 years.

Like 80 percent of migrant workers in China, Zhang is under 35 and works in the service industry, which along with construction and manufacturing employs most migrant workers.

But his story, told in the UNFPA's youth supplement, is atypical. Although most workers have only a middle school education, Zhang finished high school and attended business school in Tianjin.

His salary is much higher than the average worker's 500 to 800 yuan (US$65 to $105; euro48 to euro78) a month, according to Duan Chengrong, a demographics professor at Renmin University.

In comparison, a typical Beijing urbanite makes about 2,000 yuan (US$260; euro193) a month.

Migrant workers generally cram themselves into rented housing on the outskirts of town, with an average of five square meters (50 square feet) of living space per person and no heat, running water or sanitation facilities, Duan said.

At many construction sites, the workers lodge in ramshackle dormitories, or even in tents pitched on a nearby sidewalk.

China's government has taken measures to "avoid the emergence of urban slums and the transformation of rural poor to urban poor," said Hou Yan, deputy director of the social development department in China's Development and Reform Commission.

She mentioned programs such as establishing a minimum living standard, providing medical and educational assistance, and supplying affordable housing and basic public services. Hou did not give details of the programs.

China's urbanization is unique in that it stems largely from migration instead of natural population growth.

The Communist government that took control in 1949 imposed residency rules as part of strict controls on where people could live, work or even whom they could marry. It was not until recent years that rising wealth and greater personal freedoms eroded the system, allowing farmers to move to cities.

The UNFPA estimates that, in less than a decade, China will have 83 cities of more than 750,000 people.

Zhang, who spoke at the news conference where the UNFPA report was released, believes cities are the future of China. Before taking the job at the karaoke club, he made money teaching Chinese to foreign students, selling phone cards and running a copy shop.

"In order to get employed, what is most important is to be diligent," he said. "Only when you work hard can you get good results."