Critics have charged that Beijing’s plans for a “Green Olympics” have magnified dependence on water, pumping more and more from sources that are already over-used, including strategic reserves of deep underground supplies.

“The deep underground water is under strict protection in China because this is a strategic resource and we do not permit its development,” Gao Erkun, an official with the Ministry of Water Resources, told a news conference.

“For Beijing during the Olympic Games, there is no development or exploration of deep groundwater,” he said.

In a report released earlier this year, conservation group Probe International charged that Beijing had begun drawing on “karst” groundwater supplies more than a km (half a mile) below the surface — supplies meant to be used only in times of war or emergency.

China has also rushed to finish canals in neighbouring Hebei province able to pump 300 million cubic metres of water to Beijing, which has been beset by long-term drought.

Farmers there have complained that they have lost land and been forced to switch from growing wheat to less water-intensive corn as a result of the scheme.

Gao said the government had not diverted water from Hebei to Beijing for the Games and that it had a sustainable plan for water resources development in the megacity of 15 million.

Probe has called China’s reliance on engineering projects to deliver new water supplies misguided, instead counselling improvements in efficiency through pricing and better enforcement of existing laws to prevent profligate development.

The Beijing Games have not only seen a building spree, including many new golf courses in the suburbs, the city has also planted expanses of greenery to cover some 8,800 hectares and planted 40 million potted flowers.

The Water Resources Ministry said usage was not a concern.

“I believe the Olympic Games will not pose a big challenge to water supplies in the city,” said Hu Siyi, a deputy director at the ministry.