The US accounting standards setter has unveiled tough new rules that will increase the amount of money banks have to set aside to cover soured loans and bonds. The proposed rules from the US Financial Accounting Standards Board are likely to prove controversial among bankers, as well as FASB’s counterparts at the International Accounting Standards Board. FASB has yet to undertake an official study estimating the impact of the proposed rules, but its chairman, Leslie Seidman, said on Thursday that feedback from financial institutions indicated banks might have to increase their loan loss reserves by 50 per cent. The board will further examine the impact of the rules as it collects industry reaction, which is expected to continue into next year.