Police may review criminal action taken against four drivers of Mitsubishi trucks and buses in connection with accidents that resulted in injuries, because the vehicles may have been faulty, officials said Friday.

The vehicles in question were recently found to have been equipped with defective parts.

Police nationwide are reinvestigating 12 traffic accidents involving Mitsubishi vehicles fitted with defective components. It has been learned that investigation papers on four drivers have been sent to prosecutors over the past decade.

None of the drivers was indicted, but police authorities plan to re-examine the cases to see whether the accidents were caused by defective parts and whether it was appropriate to hold the drivers responsible, the police officials said.

Earlier this month, Mitsubishi Fuso Truck & Bus Corp. announced that Mitsubishi Fuso vehicles fitted with defective parts had been involved in 12 traffic accidents that resulted in injuries, prompting police to reopen their probes of the cases.

Mitsubishi Fuso had earlier covered up these defects.

The four drivers -- in Tokyo, Kanagawa, Osaka and Hyogo prefectures -- were suspected of violating the Road Traffic Law and of professional negligence resulting in bodily injury, the officials said.

The truck and bus maker, spun off from Mitsubishi Motors Corp. in 2003, is embroiled in a massive vehicle defect coverup scandal.

Katsuhiko Kawazoe, former head of Mitsubishi Motors, and other former MMC and Mitsubishi Fuso officials have been arrested on suspicion of professional negligence or of covering up defects in connection with a series of accidents involving Mitsubishi vehicles.

The maker made the 12 truck and bus accidents public after the first scandal broke. The 12 accidents subject to the review occurred in Tokyo, Miyagi, Kanagawa, Gifu, Shizuoka, Osaka, Hyogo, Nara and Ehime prefectures between April 1994 and February 2003.