More than a quarter of Chinese cities are at risk from tens of thousands of run-down reservoirs, prompting the government to speed up efforts to make repairs, state media said Friday.

More than 40,000 reservoirs around the country have been in use longer than their design life and are poorly maintained due to a lack of funds over the past few decades, the state-run Global Times reported.

As a result, more than 25 percent of Chinese cities and vast rural areas are at threat from potential devastating floods if dams break, it said, citing the state-run China Economic Weekly magazine.

"These reservoirs are running high risks, and will ruin farmland, railways, buildings and even cities when they collapse," said Xu Yuanming, an official in charge of reservoirs at the water resources ministry, according to the report.

The ministry was not immediately available for comment.

Ecologists have long feared about the safety of China's 87,000 reservoirs, and the giant and controversial Three Gorges Dam project in central Hubei province has caused particular concern.

The government has long held up the world's largest hydroelectric project as a symbol of its engineering prowess, a solution to the frequent floods of China's long Yangtze river and a source of badly-needed electricity.

But the dam has created a reservoir stretching up to 600 kilometres (370 miles) through a region criss-crossed by geological faultlines.

Critics fear seismic disturbances or a huge earthquake could cause a catastrophe worse than the 1975 tragedy in neighbouring Henan province, when 62 dams collapsed due to pounding rain triggered by a typhoon.

At least 26,000 people were killed in floods unleashed by the dam failures, and another 145,000 are said to have died from subsequent epidemics and famine.

To address the pressing problem, the government has launched its largest ever campaign to repair and improve the capacity of water conservancy projects in the country, the Global Times report said.

In July last year Beijing ordered 5,400 reservoirs to be reinforced, and in April started repairing another 41,000 smaller ones, it added.

However, irrigation experts have warned that a shortage of financial support and slow action by local governments could undermine this wide-ranging effort, it said.