The Securities and Exchange Surveillance Commission has begun investigations with an eye to filing a criminal complaint against three former Toshiba Corp. presidents over falsified financial reports, a market source said Thursday.

Japan's securities watchdog will examine whether to seek criminal prosecution of former President Hisao Tanaka and his predecessors, Norio Sasaki and Atsutoshi Nishida, who are suspected of instructing subordinates to misreport the results of the company's loss-making personal computer business.

Since the accounting scandal emerged earlier this year, Toshiba has revised downward by ¥224.8 billion ($1.83 billion) its pretax profits from April 2008 to December 2014.

Improper accounting practices were found in recording transactions by its infrastructure, television and semiconductor units in addition to the personal computer business.

The SESC is also set to recommend to the Financial Services Agency imposing a fine of about ¥7.4 billion on Toshiba over the accounting scandal.

The Japanese manufacturer is seeking ¥300 million in a damages suit filed against five former executives, including the three presidents who stepped down over the fiasco.