Chilean copper firm Codelco has asked for a rise in the surcharge on contract sales of copper to Chinese customers to US$85 a metric ton next year, Bloomberg reported. The request for the rise, as much as 18% higher than the 2009 surcharge, was made during ongoing pricing negotiations with China, sources involved in the negotiations said. Heavy stimulus spending and stockpiling in China have contributed to a global rise in the price of copper this year. Stockpiles in China have reached five-and-a-half year highs, while imports have risen. Analysts said the higher surcharge might be too high given likely lower demand next year as stimulus spending winds down.