China's outsourcing service is promising as it has witnessed fast expansion with optimized structural adjustments over the past few years, officials attending the 4th Global Outsourcing Summit said Monday.

"China's outsourcing service has become a green engine for economic development and will have a strong influence on the urban economic transformation," said Huo Jianguo, director of the Chinese Academy of International Trade and Economic Cooperation.

According to Huo, the number of China's outsourcing companies had exceeded 10,000 by the end of 2010 and these companies had created some 2.3 million jobs.

Outsourcing, or sub-servicing, refers to the contracting out of business that is otherwise performed in-house.

Figures from the Ministry of Commerce show that China's offshore outsourcing contracts totaled $14.5 billion in 2010, up 43 percent year-on-year.

In the first four months of this year, offshore outsourcing contracts more than doubled from a year ago to $5.2 billion, according to the ministry.

"Outsourcing has become a key factor in China's urban economic transformation," said vice-minister of commerce Wang Chao.

As China is abundant with human resources, it should make full use of this advantage to develop not only processing and trade but also the outsourcing service, said former vice-minister of commerce Wei Jianguo.

More than 600 business leaders from 44 countries and regions are attending the outsourcing summit that opened Monday in Ma'anshan, East China's Anhui province.