China's first subway tunnel traversing the Yangtze River is expected to begin construction this month in Wuhan, capital of central China's Hubei province, local officials said Saturday.

The 3,100-meter-long tunnel is located between the country's first bridge on the river, the Wuhan Yangtze River Bridge, and its first road tunnel beneath the river, officials said.

The subway tunnel is expected to undertake 50 percent of the city's traffic flow across the river. And it is designed to withstand a 6.0-magnitude earthquake and a flood that occurs once every 300 years, they said.

The tunnel is part of the city's No 2 metro line with a length of 27.98 km, which is expected to be completed in 2012.

About 14.9 billion yuan ($2.2 billion) will be invested in the construction of the metro line, officials said.

The first road tunnel was built in Wuhan, and opened for traffic since last December.

Another two road tunnels under the Yangtze River in Shanghai and Nanjing, captial of East China's Jiangsu Province, are expected to open for traffic respectively at the end of this year and in July, 2010.

The 6,300-km-long Yangtze River, which originates in Northwest China's Qinghai province and flows through 10 provinces and municipalities before emptying into the East China Sea, is a major transport link between the west and east China. More than 100 bridges across the river are in use.