China Unicom, the second-largest telephone service provider, announced Wednesday it will start offering Blackberry smartphones and 3G service in China.

China Unicom said it will first launch commercial trials of the 3G Blackberry handsets in Beijing, Shanghai and Guangdong and will gradually expand the service nationwide by September.

Research In Motion (RIM), the company that develops Blackberry, will initially sell the smartphone in retail outlets, said RIM China president Xie GuoRui. Xie also repeatedly emphasized RIM’s ambition to expand presence in the small- and medium-sized business market in South China.

RIM’s core competence comes from its dominance in push mail service and its strict control in almost all Blackberry-related products, including terminal handsets, server, client software and solutions.

With the rising potential of IT consumer market and Blackberry’s expansion in the Chinese market, the competition among the country’s three telecom carriers to increase market share in the high-end and business market will escalate, said an industry analyst.

China Mobile and China Telecom have already launched BlackBerry handsets in China, while China Unicom is the country’s only carrier that offers Apple’s popular iPhone handsets.