Last month, Japan's No. 2 automaker recalled 1.2 million vehicles, including all passenger cars it produced for sale in Japan over the past three years, after discovering that for decades, uncertified inspectors were signing off on vehicle checks required by Japan's Transport Ministry for cars sold in the country.

"Headcount reduction rates allocated to each plant applied uniformly across the whole plant, and special consideration was not given to secure final inspectors," it said in a report.

"Therefore, the plants had a shortage or no surplus in the number of final inspectors."

(Reporting by Ritsuko Ando; Editing by Minami Funakoshi)