Brussels has warned the international accounting standard-setter that a drastic shake-up of fair value rules for banks could induce more uncertainty in their accounts. The European Commission has sent a letter to the International Accounting Standards Board with some of its considerations over the board's proposals for financial institutions, due to be published this week. Debate over fair value accounting rules continues amid the financial crisis, with the IASB making attempts to adapt the accounting rule, which has been blamed by some for causing the banks' heavy losses, due to them having to mark the value of their assets at current market price when those markets were collapsing. Standard-setters from both sides of the pond are still working to find common ground on their views towards fair value. The US Financial Accounting Standards Board wants to expand the rules to cover a wider range of financial assets, while the IASB is lobbying to value assets at amortised cost, which would give information on expected cashflow. The EC has argued that reform does not go far enough to limit the use of fair value accounting, the Financial Times reports. In the letter to the IASB, Juergen Holmquist, director general of internal markets at the EC, said the new proposals could lead to more assets being marked under fair value than are under current rules, and urged the standard-setter to 'urgently' consider further changes.