A ceremony in the middle of the 36-km cable-stayed structure, which spans Hangzhou Bay in Zhejiang Province south of Shanghai, marked the official opening before several hundred spectators, Xinhua said.

The 11.8 billion yuan (S$2.3 billion) span will open to traffic on a trial basis at midnight, shortening travel time between Shanghai and Ningbo, two key port cities in China's prosperous Yangtze River Delta, to two-and-a-half hours from four.

Trucks, overloaded vehicles and vehicles carrying dangerous chemicals will be barred from the bridge during the trial period, Xinhua said.

'We haven't decided how long the trial operation period will last. That depends ... on the bridge condition, and we need time to improve management about its operation,' it quoted Mr Jin Jianming, deputy chief commander of the bridge construction project, as saying.

The bridge is China's first major public infrastructure project to receive investment from the country's private sector, which funded almost 30 percent of the cost, the report said.

China, the world's fourth-largest economy, is spending heavily on infrastructure to maintain its double-digit rates of economic growth. It began construction of the bridge in November 2003. -- REUTERS