The wetlands along northern China's biggest river system are drying up because of the thirst of an expanding population and a fast-growing economy, Xinhua news agency reported on Sunday.

Xinhua said 12 main sections of wetlands along the reaches of the Haihe River, which used to cover 3,800 sq km (1,465 sq miles), have shrunk by more than 80 percent over the past five decades to just 538 sq km (207 sq miles).

The Haihe is formed by five large rivers that spread out like a fan over vast areas of northern China and converge near Tianjin, a bustling port city southeast of Beijing.

One of China's three main river valleys, its basin covers an area of 320,000 sq km (125,000 sq miles).

Xinhua quoted officials with the regional water conservancy authority as blaming the shrinking of the wetlands on excessive exploitation of the Haihe and damming of the river's tributaries.

"Water resource experts attribute the worrisome environmental changes to overuse of ground water by a growing population and rapid economic development along the river," the agency said.

China's ruling Communist Party, increasingly worried about the environment costs of breakneck growth, has made water and energy conservation a priority of its just-begun five-year plan.

The expansion of thirsty industries such as paper and cement has strained water supplies to the limit in a country that only has one fourth as much water, per head of its population, as the world average.

An estimated 300 million people nationwide have no access to clean water, 70 percent of China's water is contaminated and in the past 50 years year it has lost more than 1,000 lakes.