The survey, conducted by Accountancy Age's sister magazine Financial Director in association with Resources Connection, found that while audit costs are rising and other fees are falling following the introduction of Sarbanes-Oxley and the combined code, audit still accounts for less than half of the fees charged to FTSE100 clients.

For a PDF download of the entire survey, click here:

Link: The eigth annual FTSE350 audit fees survey

In total, audit fees in the FTSE100 rose 16% over the year to £274.4m, with Ernst & Young registering the biggest jump, up 46% to £37.8m. Other fees fell sharply, but the 21% drop to £356.7m still outweighs money taken from audit.

PricewaterhouseCoopers registered the biggest drop, down 34% to £143.6m, while Deloitte, the only firm to retain its consulting business, saw other fees rise 5% to £69.7m.

PwC brought in the most auditor fees from the FTSE350, accounting for 40%. KPMG came second with just under 25%, while Deloitte and Ernst & Young were roughly level.

Oil company Shell had the most expensive audit during the past year, at a cost of £19.4m, with other fees adding another £14.5m. Unsurprisingly, given the problems with the company's oil reserve valuations, the audit also took the longest to sign off, at 143 days. Supermarket chain Morrisons had the most cost-effective audit with KPMG charging just £28 per £1m of turnover. Investment group 3i was charged £3,042 per £1m by Ernst & Young.

A separate survey by the ICAEW has shown that this increase in audit fees is not going to waste, with fund managers expressing increased confidence in the audits of UK companies.

Of those asked, 87% of UK fund managers expressed a 'great deal' or a 'fair amount' of confidence in audited financial information, while just 56% of US fund managers shared this view of UK figures.