Former Olympus chairman Tsuyoshi Kikukawa has been arrested as part of the continuing investigations into the camera company, according to Japanese media. The firm is being probed for an accounting cover-up after it admitted to hiding $1.7bn (£1bn) in losses for two decades. Mr Kikukawa resigned in October after the scandal broke out. Olympus has sued 19 former and current executives over the issue. \"This is the first solid increment, taking a system that has governed itself on informal rules, to the one that is based on formal rules and law,\" Kenneth Cukier of The The scandal broke out in October after former chief executive Michael Woodford claimed he was fired for raising concerns about the company\'s accounting practices. Mr Woodford pointed out that he had questioned Olympus\' payment of $687m in fees to financial advisers during the acquisition of UK medical equipment company Gyrus. Although the company initially denied the allegations, it later admitted that it had been hiding losses for as long as 20 years. The scandal resulted in the company\'s shares plunging more than 50% on the Tokyo Stock Exchange (TSE). The TSE had also placed the stock under a watch list as the firm delayed filing its latest accounts in the wake of the scandal. Analysts said the latest developments were a victory for the firm\'s shareholders. \"It is game over for Kikukawa and other people who have frauded the company and its shareholders of billions of dollars,\" said Mr Cukier. \"This is a day that anyone who believes in the rule of law should be celebrating.\"