Industrial & Commercial Bank of China, the nation's biggest lender, has advised banks and forex interests to use derivatives to hedge against coming fluctuations in the RMB, Bloomberg reported. China recently re-authorized derivative sales after years of prohibition. The People's Bank of China will also permit Hong Kong lenders higher RMB trading volumes. Hong Kong banks were disappointed, expecting more, the South China Morning Post reported, but retailers welcomed the expansion, said the Hong Kong Standard.