The International Accounting Standards Committee Foundation has written to US president Barack Obama ahead of a G-20 summit in Pittsburgh next week, to defend the International Accounting Standards Board's new stance on fair value accounting rules and to state it has made 'substantial progress' on the G-20 objectives it was set in April. Objectives set included global convergence towards accounting standards, and looking into remodelling its fair value rules that force banks to value their assets at current market price - blamed by many in the banking sector as fuelling the crisis. But the IASC Foundation defended the IASB's stance on fair value, stating: 'In making their proposals and in order to provide transparency and reflect economic reality, the IASB's emphasis has been to define in a balanced and transparent way the appropriate criteria for classifying instruments to be measured at cost and fair value - not to increase or decrease arbitrarily the use of fair value. 'The IASB is not proposing that the loan book of banks will be held at fair value,' it added.