China, the world's second-biggest energy user, ordered a cap on prices of power-station coal at major ports to help electricity producers cope with costs as the nation battles a sixth year of power shortages.

Ports including Qinhuangdao, Tianjin and Tangshan aren't allowed to sell thermal coal at prices higher than June 19 levels, the National Development and Reform Commission said in a statement on its Web site today.

Most of China's power plants are losing money because of rising coal prices and government controls on electricity tariffs. The commission ordered a cap on prices of coal at mines on June 19. The restriction failed to prevent prices from rising at ports, which climbed 22 percent in a month, the Beijing News reported today.

``This will, to some extent, help power companies reduce fuel purchasing costs,'' David Fang, a director of information at the China Coal Transport and Distribution Association, said by mobile phone from Beijing today. ``They are unlikely to ease the coal shortages in the short-term.''

Prices of coal with 5,500 kilocalories are capped at 860 yuan ($126) a metric ton at Qinhuangdao port, 840 yuan a ton at Tianjin and 850 yuan a ton at Tangshan, the commission said today. Kilocalories are a measure of the amount of energy coal generates when burnt.

The government will punish any coal producers that raise prices illegally, it said.

Coal Producers' Shares

Shares of China Shenhua Energy Co., the nation's biggest coal supplier, fell as much as 4.4 percent in Hong Kong trading. China Coal Energy Co. dropped 4 percent.

China relies on coal for almost 80 percent of its electricity generation. Insufficient fuel supplies forced the closure of 2.5 percent of the nation's coal-fired power plants, State Grid said on July 7. Government restrictions on transporting hazardous materials near Olympic venues also disrupted some coal production, Zhang Wenjiang, assistant general manager of Shenhua Group Corp., said last week.

The world's fastest-expanding major economy faces such acute power shortages that electricity-sapping industries including aluminum smelters have had to halt production.

Economic Growth

Energy supply shortages have become a ``key factor'' in holding back the nation's economic and social development, the Chinese government said in a statement yesterday.

To conserve energy and cut the nation's demand for oil, Chinese Premier Wen Jiabao ordered the nation to cut back on summer air conditioning and drive less, according to yesterday's statement. The nation will also shut more oil-fired power generators, it said.

Wen will raise a consumption tax on vehicles with large- capacity engines, according to the statement, which neither specify the tax nor give the engine size. Low-emission vehicles and energy-efficient autos powered by gasoline-electric hybrid systems will get tax breaks.

The government will develop public transport, urging the public to drive at least one day less each week, the statement said. Street lamps, hotels, and public venues will have to switch to energy-efficient lights this year, the government said.