The multi-billion dollar project is expected to alleviate severe water shortages in northern China, especially in Beijing, but the human, environmental and financial costs have elicited strong opposition.

On Tuesday, work on two 19 kilometer (11 mile) water transport tunnels to span the Yellow River began near Zhengzhou, the provincial capital of Henan province, the China Daily reported.

The 386-million-dollar tunnel project will be a complex engineering task as the tunnels will be built 60 meters below the bottom of the Yellow River, China's second largest.

Xinhua news agency said work also began this week on the Danjiakou Dam in neighboring Hubei province, where the diversion project will originate. The height of the 1950s-era dam must be increased by 14 meters.

The extra height will expand the Danjiakou reservoir and force the relocation of up to 200,000 people.

Some 200,000 others are expected to be displaced along the rest of the route north, which will be made up of tunnels, canals, pipelines and pump stations, it said.

The project's central Danjiakou-Beijing route is expected to transport up to 10 billion cubic meters of water to the north by 2010.

The eastern section is largely completed and follows along the historic Grand Canal built more than 1,500 years ago. It is also expected to transport 10 billion cubic meters of water by 2010.

A western section is to skirt the foothills of the Tibetan plateau and could costs billions of dollars more and require complex engineering tasks to pump water over mountainous areas.

Naysayers have expressed fears that even if the water can be diverted to Beijing and northern China, the water will be too polluted to use as China's water quality ranks among the worst in the world.

Environmental groups have also opposed the plan because the Yangtze river ecosystem could be affected by the loss of water, while the National People's Congress or parliament has been concerned over costs.

Despite opposition, the schemes for the central and eastern lines have been approved.

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