Officials at LCD panel-maker Japan Display say an accountant it fired on suspicion of embezzlement may have engaged in additional improper activities.
The loss-making company fired the executive last year.
The officials at Japan Display, or JDI, say the accountant notified the company of the additional misconduct on Tuesday.
The company accuses the person of embezzling about 5.3 million dollars during a roughly four-year period to October last year. JDI filed a criminal complaint with police.
In the latest disclosure, the officials say the former accountant has admitted to conducting improper accounting in the past at the direction of the firm's then-management.
But they added that the firm's earnings reports have always been closely examined and they believe that accounting in the past had been done properly.
Even so, the latest development has prompted the company to consult its auditing firm and check its past books.
JDI also plans to ask outside experts to investigate the case.
The company is in negotiations with a state-backed fund and others in a bid to turn around its struggling business.
The officials say they have explained the recent disclosure to the fund and other firms taking part in the bailout plan and have received their understanding.