Aon Corporation will restate more than three years of its financial results after an internal audit committee uncovered irregularities in its accounts. The Chicago-based brokerage has begun a comprehensive review of how, and when, it accounts for certain stock options.

While the problems go back a long way, Aon plans to only restate the group’s financial results for the three years between 2003 and 2005, as well as the first three quarters of last year. It says the problem had very little impact on its accounts prior to those years, with even the total error relatively small. “The cumulative impact of the delegated grants and other administrative errors from 1994 to 2006 amounted to $US66 million ($85.8 million) pretax,” it told the Securities and Exchange Commission last week.

The audit committee says it does not believe there has been any misconduct or attempt to influence the company’s share price.