July 11 (Bloomberg) -- China's aluminum producers, the world's largest, are unlikely to cut output as promised because record prices offer substantial profit margins, analysts said.

     Aluminum jumped to a record yesterday after China's top 20 smelters, who account for 70 percent of the nation's output, agreed to cut production by 5 to 10 percent to alleviate a power shortage. The reductions will last at least through September, the China Nonferrous Metal Industry Association said today.

     ``We don't think the producers will really do what the association proposes given they have a fat profit to earn, up to 1,500 yuan ($219) per ton,'' Bonnie Liu, an analyst at Macquarie Group Ltd, said today by phone from Shanghai. ``Even if they do as promised, the production loss would be offset by a global surplus'' of between 750,000 and 800,000 tons this year, Liu said.

     Global aluminum prices are affected by Chinese output as the nation is a net exporter of the metal used in construction and aircraft manufacture. Exports of aluminum and alloys jumped 43 percent to 123,538 metric tons in June from the previous month, customs data showed. That's the highest since August 2006.

     Aluminum for delivery in three months on the London Metal Exchange fell 0.2 percent to $3,285 a ton at 1:38 p.m. in Shanghai after rising as high as $3,380 a ton yesterday. London prices have gained 37 percent this year on earlier output cuts in China and South Africa, outpacing a 10 percent surge by Shanghai futures.

                    `Anyone's Guess'

     ``It's anyone's guess whether the producers will really do what they say,'' Eric Zhang, an analyst at CBI China Co., said in an e-mailed report today. Chinese aluminum producers made a similar pledge in 2005, when an alumina shortage caused losses, but the cut turned out to be less than expected, Zhang said.

Alumina is a material used to make aluminum metal.

     Reducing output is aimed at alleviating China's sixth year of power shortages caused by rapid economic growth and ensure electricity supplies for the Beijing Olympics next month. The energy used by China's aluminum smelters each week is enough to provide power for more than 2 million people for a year.

     Still, ``aluminum producers without their own power plants are more likely to abide by their word as they could incur higher production costs'' than the industry average of between 17,000 and 18,000 yuan per ton, Wan Ling, an analyst at CRU International Ltd, said by phone from Beijing today.

     Many of China' top aluminum makers such as Henan's Yugang Longquan Aluminum Industrial Co. and Shandong' Xinfa Aluminum and Electricity Group have their own power plants, Wan said.

     Should the production cuts be implemented and last until the end of the year, China may see output reduced by 198,000 to 396,000 tons, CBI's Zhang said, comparatively small compared with the 430,000-ton loss because of winter snowstorms.

     With current high prices, ``the Chinese way of thinking is they won't cut, not even for a good cause'' like saving the country's energy, said Macquarie's Liu.