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.

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

Also among 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 these have already been confirmed safe for continued use by the firm and its clients, according to Mitsubishi Materials.

At Mitsubishi Cable, specification data on its O-ring sealing product were altered to match those requested by client companies. Shipments of the products worth ¥29.4 billion were made between April 2015 and September this year to a total of 229 firms, including 70 in the aerospace industry as well as seven automakers.

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 that did not meet the requested specification had been installed within hydraulic components of SDF aircraft and ship engines.

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

Mitsubishi Shindoh Co., a copper product unit, falsified inspection data on products such as brass strips for automotive components. Affected products worth ¥120.9 billion 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 to confirm the details.

Mitsubishi Cable stopped shipments 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.

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

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

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