A report by the Investment Association that found no evidence that hidden fees hit fund returns wasn't shown to its own expert committee before publication, according to the committee's chair.

The disclosure adds a further element of controversy to the August 9 report, which sought to damp down the debate over disclosure of fund charges. In it the association, which represents managers of £5.5 trillion of funds, said that hidden fees were the "Loch Ness Monster of investments".