Subaru Corp. used uncertified staff to conduct vehicle inspections at two plants in Gunma Prefecture, north of Tokyo, for more than 30 years, a company executive said Friday.

A Subaru executive admitted to reporters that workers who were in training for the task but still lacked certification were conducting inspections. "This practice has been traditionally carried out for more than 30 years," the executive said.

The Japanese carmaker is expected to announce the findings shortly, probably later in the day. The company will decide whether it needs to conduct a recall after discussions with the Ministry of Land, Infrastructure, Transport and Tourism, the sources said.

The inappropriate inspection practice at Subaru, which comes on the heels of the discovery of similar practices by Nissan Motor Co., is just the latest in the string of corporate scandals in the country, tarnishing Japan Inc.'s reputation for high quality.

Nissan has halted new car shipments for the domestic market at all of its six domestic plants for finished cars, recalling a total of some 1.2 million vehicles. Japan's third-largest steelmaker Kobe Steel Ltd. has also been engulfed in a data fabrication scandal after revealing that data for materials including aluminum and copper had been compromised.

According to sources close to the matter, Subaru allowed uncertified workers in training to conduct a part of the safety checking process on vehicles at two plants in Ota in the eastern Japan prefecture. The uncertified inspectors were also using stamps of authorized technicians to sign off on documents, the sources said.

There are roughly 250 authorized inspectors at Subaru who are entitled to do final vehicle inspections. But a part of the inspections was done by workers still in training at the two plants.

The carmaker issued a temporary permit to workers who had gone through some training that allowed them to conduct final vehicle checks, with the aim of having them gain experience.

The misconduct was found during the automaker's in-house probe following a transport ministry order issued after the problem at Nissan came to light in September.

Meanwhile, six other Japanese automakers -- Toyota Motor Corp., Honda Motor Co., Mazda Motor Corp., Mitsubishi Motors Corp., Suzuki Motor Corp. and Daihatsu Motor Co. -- have already reported to the transport ministry that no problems were found in their inspection system.

In April, Subaru changed its corporate name from Fuji Heavy Industries Ltd., using the popular label of its cars. The carmaker originally started out as Nakajima Aircraft Company in 1917 which produced airplanes during the war.

The company reported group sales of 3.33 trillion yen ($29 billion) for fiscal 2016. There are a total of roughly 32,000 employees in the Subaru group.