China's software industry continued to expand during the first four months of this year, with business income up 28 percent on the previous year, the Ministry of Information Industry said on Friday.

The sources said the sector garnered 143.5 billion yuan (18.6 billion U.S. dollars) in revenue between January and April.

Of the total, software products accounted for 51.2 billion yuan (6.6 billion U.S. dollars), up 27.9 percent, and system integration, covering IC design and solution design, 34.9 billion yuan (4.5 billion U.S. dollars), up 27.7 percent.

In recent years China has tried to boost the development of its software services but the share of this sector in the total income of the software industry was down 6.6 percent compared with the 2006 level.

The first four months witnessed a continued imbalance between software products, system integration and software services, industry sources said.