Three former executives at Olympus Corp., including ex-chairman Tsuyoshi Kikukawa, and four others were arrested for suspected violation of Japan's Financial Instruments and Exchange Act.

The camera maker is facing shareholder lawsuits and may be subject to further criminal investigation after admitting to a 13-year cover-up. The company restated past securities reports and took a $1.3 billion reduction in net assets in December.

Olympus's Tokyo headquarters and its affiliated offices were raided in December by prosecutors after the company said Kikukawa and two others colluded to hide investment losses from the 1990s. The stock has plunged 49 percent since the Oct. 14 dismissal of its first non-Japanese president, Michael Woodford, who later publicly questioned inflated takeover costs.