Mitsubishi Materials Corp saw its stock fall as much as 11 percent on Friday after it said three subsidiaries had falsified product data, marking the latest in a series of quality assurance scandals involving Japanese manufacturers.
Mitsubishi Materials said inspection data was falsified on parts used in aircraft, automobiles and industrial machinery, with potentially more than 250 customers affected.
The admission follows a spate of compliance failings at Japanese manufacturers including Kobe Steel Ltd, Nissan Motor Co Ltd and Subaru Co Ltd.
Minister of Economy, Trade and Industry Hiroshige Seko on Friday said the latest misconduct was "a betrayal of trust in Japanese manufacturing," pointing to the amount of time Mitsubishi Materials took to reveal the wrongdoing.
Mitsubishi Materials said data falsification at subsidiary Mitsubishi Cable Industries Ltd was discovered as far back as February.
The unit distorted data on around 20 percent of its rubber sealing products, used in aircraft and cars, for two-and-a-half years from April 2015. Of 229 potentially affected customers, 40 have been informed by the company.
Another subsidiary, Mitsubishi Shindoh Co Ltd, manipulated data for metal products, used in cars and electronics, as far back as October 2016. Around half of 29 potentially affected customers have been informed.
Mitsubishi Materials said it stopped shipping affected materials from the two units in October.
In both cases the company said it had not found any safety or legal problems.
A third subsidiary, Mitsubishi Aluminum Co Ltd, also shipped products which did not meet specification, with the safety of the affected products already confirmed with customers, the parent said.
Mitsubishi Materials said it did not know whether there would be any impact on its financial outlook and has set up a task force to look into the problems and to devise countermeasures to improve quality control.
With affected Mitsubishi Materials products used in defense equipment including aircraft engines, Japan's defense ministry is working to establish the impact of the wrongdoing but does not currently plan to stop using any equipment, Defense Minister Itsunori Onodera said on Friday.
The company reported to the transport ministry around midday today, a ministry spokesman said.
The admission came after Japanese consumers saw a series of quality control and governance lapses at major firms including Kobe Steel, Nissan and Subaru.
Kobe Steel has admitted falsifying strength and quality data for a string of products shipped to hundreds of clients, from automakers to plane manufacturers.
Nissan recalled some 1.2 million vehicles after admitting in October that staff without proper authorisation had conducted final inspections on some vehicles intended for the domestic market before they were shipped to dealers.
Subaru also recalled nearly 400,000 vehicles from its domestic market after admitting that it also allowed uncertified staff to conduct vehicle inspections.