Mitsubishi Materials Corp. said Thursday that three of its subsidiaries have falsified specification data for products supplied to the aerospace, automotive and electric power industries.

The revelation comes on the heels of quality control scandals at other major Japanese firms, including a metal product data falsification scandal at Kobe Steel Ltd.

One of the subsidiaries' rubber products not meeting specification requirements of the Self-Defense Forces were used in some of the engines of their aircraft and vessels, according to officials at a government agency responsible for development and procurement of defense equipment.

Of the three firms, Mitsubishi Cable Industries Ltd. falsified data on sealing materials used for joining metal parts such as pipes supplied to 229 firms, and Mitsubishi Shindoh Co. rigged data on copper products shipped to 29 companies. None of the cases have been found to have caused any safety problems so far, Mitsubishi Materials said.

Another unit Mitsubishi Aluminum Co. also supplied products with falsified specification data, but it and client firms have already confirmed that they are safe for continued use, according to Mitsubishi Materials.

At Mitsubishi Cable, specification data on its O-ring sealing product were altered to match those requested by client companies.

Such products worth 29.4 billion yen ($264 million) were shipped between April 2015 and September this year to a total of 229 firms, including 70 in the aerospace industry and seven automakers.

The O-rings are commonly used as packing and gaskets in joining pipes and other metal products to prevent oil, water and air from leaking, according to Mitsubishi Cable.

Officials of the Acquisition, Technology and Logistics Agency under the Defense Ministry said products including rubber seals not meeting requested specification are installed in hydraulic components of SDF aircraft and ship engines.

While the agency is still investigating which equipment has the affected products installed, Mitsubishi Cable told the agency that any impact on the performance of the products in question is not serious enough to require an immediate suspension of operation, agency officials said.

Mitsubishi Shindoh falsified inspection data on such products as brass strips for automotive components.

Affected products worth 120.9 billion yen were supplied to 29 firms between October 2016 and last month, Mitsubishi Shindoh said.

Mitsubishi Materials said the problem at Mitsubishi Cable surfaced after its quality control auditing led the subsidiary to start an internal probe last December. It discovered data falsification in February and continued the investigation for confirmation of details.

Mitsubishi Cable stopped shipment of the affected products on Oct. 23 and reported its findings to Mitsubishi Materials two days later.

Mitsubishi Shindoh started an internal probe last month and discovered the data falsification.

Quality control scandals have also rocked the automotive industry recently, with Nissan Motor Co. and Subaru Corp. revealing that unauthorized staff conducted final vehicle inspections, resulting in extensive recalls.

Mitsubishi Cable and Mitsubishi Shindoh said they have each set up a probe committee whose members include outside lawyers to conduct a detailed investigation and compile preventive measures.

Mitsubishi Materials said it will hold a press conference Friday regarding the matter.