Construction began in November 2004 on the 1.7 billion yuan (S$359 million) tunnel, which stretches for 2 miles (3.5 kilometres) under China's longest river, the official Xinhua News Agency said.

The four-lane road connects Wuchang district - which is home to government offices and universities - to the business district of Hankou, and was expected to cut travel time between the two areas from a half-hour to just a few minutes, Xinhua said. It should also relieve traffic congestion in the city of 8 million people, the report said.

The Yangtze River cuts through China's most heavily populated regions and is a lifeline to tens of millions of people. -- AP