Toshiba Corp. has announced it might have to revise operating profit downward by just over ¥50 billion ($412 million) for the three years through March 2014 because of an in-house investigation into improper accounting at its infrastructure-related businesses.

The estimate, contained in a statement the company issued late Wednesday, compares with about ¥695 billion in operating profit reported over the period. It was the first hint about the potential impact the accounting problem might have since the electronics conglomerate withdrew its earnings forecasts last week and warned it may have to revise earnings.

Toshiba might form a panel of outside experts versed in legal affairs and accounting to conduct a detailed probe into the matter as early as this week. The probe might come up with a different estimate for a revision, the company said.