The Japanese Institute of Certified Public Accountants said Thursday that 392 accountants at Japan's four largest auditing firms have worked with the same clients for at least seven years.

A revised law governing certified public accountants that took effect in April 2004 bans auditors from working with the same clients for more than seven years.

The figure accounts for about 30 percent of all four firms' accountants responsible for company audits, the JICPA told a study panel ruling of Liberal Democratic Party on corporate accounting.

As of March 31, the 392 accountants from KPMG Azsa & Co., Ernst & Young ShinNihon, ChuoAoyama PricewaterhouseCoopers and Tohmatsu & Co. had audited the books of 580 companies for seven years or longer, JICPA said.

Cozy relations between auditors and client companies resulting from long-standing business ties have drawn strong public criticism in the wake of ChuoAoyama's role in window-dressing Kanebo Ltd.'s financial reports.