In a letter to summit host George W Bush, trustee chairman Gerrit Zalm wrote that the IASB is committed to helping restore confidence in the financial system, but that some issues surrounding fair value are "not conducive to immediate fixes".
Fair value rules require assets to be linked to their current market price, rather than their projected mature value.
In light of recent market volatility, many financial institutions have called for them to be amended or lifted. Mr Zalm also acknowledged that some observers believe they could have escalated the present crisis by dictating the sale of assets in order to meet capital requirements.
However, he contended, many investors support the rules for providing an accurate picture of the market and he called on the G20 not to sacrifice this transparency.
A recent survey from the CFA Institute found that 85 per cent of respondents believe suspending the rules would further damage confidence in the European banking system, Mr Zalm added.