China is to invest up to 4 trillion yuan ($600 billion) over the next decade to overcome a huge water shortage that threatens the country's economic growth, a senior official said on Wednesday.

The vice minister of water resources said China's unbridled economic growth had left up to 40 percent of its rivers badly polluted and the country faced "huge pressures" on supplies of water.

"Industrialisation and urbanisation, including ensuring grain and food security, are exerting higher demands on water supplies... while our water use remains crude and wasteful," Jiao Yong said at a press briefing.

Over 46,000 reservoirs in China need to be rebuilt or reinforced to ensure that surrounding farmlands and communities are safe from flooding and have enough water for irrigation, he said.

More funding would also be needed to protect the reservoir of the $22.5 billion Three Gorges Dam -- the world's largest -- from geological disasters and pollution, he said.

The government has long held up the world's largest hydroelectric project as a symbol of its engineering prowess.

But the dam has created a reservoir stretching up to 600 kilometres (370 miles) through a region criss-crossed by geological faultlines and critics fear seismic disturbances such as a huge earthquake could cause a catastrophe.

Jiao also said the government would build more water transfer projects and hydroelectric dams and strengthen efforts to ensure the supply of safe drinking water.

China's north suffers regular droughts, while annual flooding wreaks havoc on farm areas in the south.

The government is building a huge $60 billion south-to-north project that aims to divert water to the drought stricken region around China's capital, Beijing.