Former Olympus Corp. President Michael C. Woodford, who has called into question dubious acquisitions by the firm, submitted a letter of resignation Wednesday to the company, where he had remained a director, his lawyer said.

Woodford said at a press conference held later in the day in New York that he resigned from the Japanese camera and medical equipment maker to fight a proxy battle to come back as president of the firm.

"The reason that I've done it is that I believe it would be an opportunity for me to mobilize interested parties in Olympus and those shareholders who want real change," he said.