Olympus Corp., whose shares plummeted about 50 percent after its ousted former president publicly criticized it for dubious money transactions, claimed Thursday there is nothing illicit about the advisory fee it paid in acquiring a British medical equipment firm.

"We believe we did nothing illegal," Shuichi Takayama, who became president of Olympus on Wednesday, told reporters in Tokyo. "We disclose with sincerity all the information we can."

Meanwhile, the Securities and Exchange Surveillance Commission has reportedly launched an investigation into Olympus to determine if the Tokyo-based medical equipment and camera maker appropriately disclosed information on the acquisition.