The Japan Federation of Economic Organizations (Keidanren) announced Monday it will bar Nikko Securities Co., Yamaichi Securities Co., Daiwa Securities Co. and Hokkoku Bank Ltd. from participating in its activities for a year starting today.

Chairman Shoichiro Toyoda's announcement follows the arrests of the firms' top executives in connection with illegal payoffs allegedly made to "sokaiya" corporate extortionists and other misconduct. Toyoda said the companies have submitted to him letters of intent indicating they will comply with the action.

With the announcement Monday, the number of companies suspended by Japan's most influential business organization due to business scandals reaches eight.