Government inspectors raided a factory of Japanese truck maker Mitsubishi Fuso on Thursday, reportedly on suspicion that it has continued to falsify reports on vehicle defects despite vowing to clean up its act, The Associated Press (AP) said.

The news agency noted that Fuso, 65% owned by DaimlerChrysler and spun off from Mitsubishi Motors Corp. last year, has announced massive recalls this year after acknowledging that it had hidden known defects in its vehicles’ wheels and clutch systems for years.

The company reportedly fired a manager this week after he allegedly tried to downplay the seriousness of clutch defects in a recent report following an in-house investigation.

An official at the transport ministry’s recall division, on condition of anonymity, told the Associated Press that four transport ministry officials began inspecting a Mitsubishi Fuso factory in Kawasaki city, just south of Tokyo, to check the accuracy of the company’s reports on clutch defects.

According to AP, the Japanese broadcaster NHK had said that, while the manager acted alone in compiling the misleading report, the ministry was investigating whether more people may have been involved.

Their probe reportedly is separate from a criminal investigation by police that has led to the arrest of four former Mitsubishi Motors executives, including former Mitsubishi Fuso chairman Takashi Usami.