Kobe Steel Ltd. said Friday that several employees had covered up deceptive practices in the firm, hampering internal investigations on the ongoing data falsification scandal.

The firm said when the misconduct within part of the aluminum and copper business section came to light in August, the company widened its internal investigation to the whole section and eventually to all its businesses.

However, some employees at a factory in Yamaguchi Prefecture did not report cases of data falsification after Kobe Steel expanded the investigation.